python typeerror 'tuple' object does not support item assignment

TypeError: 'tuple' object does not support item assignment

Last updated: Apr 8, 2024 Reading time · 4 min

# TypeError: 'tuple' object does not support item assignment

The Python "TypeError: 'tuple' object does not support item assignment" occurs when we try to change the value of an item in a tuple.

To solve the error, convert the tuple to a list, change the item at the specific index and convert the list back to a tuple.

Here is an example of how the error occurs.

We tried to update an element in a tuple, but tuple objects are immutable which caused the error.

# Convert the tuple to a list to solve the error

We cannot assign a value to an individual item of a tuple.

Instead, we have to convert the tuple to a list.

This is a three-step process:

• Use the list() class to convert the tuple to a list.
• Update the item at the specified index.
• Use the tuple() class to convert the list back to a tuple.

Once we have a list, we can update the item at the specified index and optionally convert the result back to a tuple.

Python indexes are zero-based, so the first item in a tuple has an index of 0 , and the last item has an index of -1 or len(my_tuple) - 1 .

# Constructing a new tuple with the updated element

Alternatively, you can construct a new tuple that contains the updated element at the specified index.

The get_updated_tuple function takes a tuple, an index and a new value and returns a new tuple with the updated value at the specified index.

The original tuple remains unchanged because tuples are immutable.

We updated the tuple element at index 1 , setting it to Z .

If you only have to do this once, you don't have to define a function.

The code sample achieves the same result without using a reusable function.

The values on the left and right-hand sides of the addition (+) operator have to all be tuples.

The syntax for tuple slicing is my_tuple[start:stop:step] .

The start index is inclusive and the stop index is exclusive (up to, but not including).

If the start index is omitted, it is considered to be 0 , if the stop index is omitted, the slice goes to the end of the tuple.

# Using a list instead of a tuple

Alternatively, you can declare a list from the beginning by wrapping the elements in square brackets (not parentheses).

Declaring a list from the beginning is much more efficient if you have to change the values in the collection often.

Tuples are intended to store values that never change.

# How tuples are constructed in Python

In case you declared a tuple by mistake, tuples are constructed in multiple ways:

• Using a pair of parentheses () creates an empty tuple
• Using a trailing comma - a, or (a,)
• Separating items with commas - a, b or (a, b)
• Using the tuple() constructor

# Checking if the value is a tuple

You can also handle the error by checking if the value is a tuple before the assignment.

If the variable stores a tuple, we set it to a list to be able to update the value at the specified index.

The isinstance() function returns True if the passed-in object is an instance or a subclass of the passed-in class.

If you aren't sure what type a variable stores, use the built-in type() class.

The type class returns the type of an object.

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

• How to convert a Tuple to an Integer in Python
• How to convert a Tuple to JSON in Python
• Find Min and Max values in Tuple or List of Tuples in Python
• Get the Nth element of a Tuple or List of Tuples in Python
• Creating a Tuple or a Set from user Input in Python
• How to Iterate through a List of Tuples in Python
• Write a List of Tuples to a File in Python
• AttributeError: 'tuple' object has no attribute X in Python
• TypeError: 'tuple' object is not callable in Python [Fixed]

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Copyright © 2024 Borislav Hadzhiev

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Tuple Object Does Not Support Item Assignment. Why?

Have you ever seen the error “tuple object does not support item assignment” when working with tuples in Python? In this article we will learn why this error occurs and how to solve it.

The error “tuple object does not support item assignment” is raised in Python when you try to modify an element of a tuple. This error occurs because tuples are immutable data types. It’s possible to avoid this error by converting tuples to lists or by using the tuple slicing operator.

Let’s go through few examples that will show you in which circumstances this error occurs and what to do about it.

Let’s get started!

Explanation of the Error “Tuple Object Does Not Support Item Assignment”

Define a tuple called cities as shown below:

If you had a list you would be able to update any elements in the list .

But, here is what happens if we try to update one element of a tuple:

Tuples are immutable and that’s why we see this error.

There is a workaround to this, we can:

• Convert the tuple into a list.
• Update any elements in the list.
• Convert the final list back to a tuple.

To convert the tuple into a list we will use the list() function :

Now, let’s update the element at index 1 in the same way we have tried to do before with the tuple:

You can see that the second element of the list has been updated.

Finally, let’s convert the list back to a tuple using the tuple() function :

Makes sense?

Avoid the “Tuple Object Does Not Support Item Assignment” Error with Slicing

The slicing operator also allows to avoid this error.

Let’s see how we can use slicing to create a tuple from our original tuple where only one element is updated.

We will use the following tuple and we will update the value of the element at index 2 to ‘Rome’.

Here is the result we want:

We can use slicing and concatenate the first two elements of the original tuple, the new value and the last two elements of the original tuple.

Here is the generic syntax of the slicing operator (in this case applied to a tuple).

This takes a slice of the tuple including the element at index n and excluding the element at index m .

Firstly, let’s see how to print the first two and last two elements of the tuple using slicing…

First two elements

We can also omit the first zero considering that the slice starts from the beginning of the tuple.

Last two elements

Notice that we have omitted index m considering that the slice includes up to the last element of the tuple.

Now we can create the new tuple starting from the original one using the following code:

(‘Rome’,) is a tuple with one element of type string.

Does “Tuple Object Does Not Support Item Assignment” Apply to a List inside a Tuple?

Let’s see what happens when one of the elements of a tuple is a list.

If we try to update the second element of the tuple we get the expected error:

If we try to assign a new list to the third element…

…once again we get back the error “‘ tuple’ object does not support item assignment “.

But if we append another number to the list inside the tuple, here is what happens:

The Python interpreter doesn’t raise any exceptions because the list is a mutable data type.

This concept is important for you to know when you work with data types in Python:

In Python, lists are mutable and tuples are immutable.

How to Solve This Error with a List of Tuples

Do we see this error also with a list of tuples?

Let’s say we have a list of tuples that is used in a game to store name and score for each user:

The user John has gained additional points and I want to update the points associated to his user:

When I try to update his points we get back the same error we have seen before when updating a tuple.

How can we get around this error?

Tuples are immutable but lists are mutable and we could use this concept to assign the new score to a new tuple in the list, at the same position of the original tuple in the list.

So, instead of updating the tuple at index 0 we will assign a new tuple to it.

Let’s see if it works…

It does work! Once again because a list is mutable .

And here is how we can make this code more generic?

Ok, this is a bit more generic because we didn’t have to provide the name of the user when updating his records.

This is just an example to show you how to address this TypeError , but in reality in this scenario I would prefer to use a dictionary instead.

It would allow us to access the details of each user from the name and to update the score without any issues.

Tuple Object Does Not Support Item Assignment Error With Values Returned by a Function

This error can also occur when a function returns multiple values and you try to directly modify the values returned by the function.

I create a function that returns two values: the number of users registered in our application and the number of users who have accessed our application in the last 30 days.

As you can see the two values are returned by the function as a tuple.

So, let’s assume there is a new registered user and because of that I try to update the value returned by the function directly.

I get the following error…

This can happen especially if I know that two values are returned by the function but I’m not aware that they are returned in a tuple.

Why Using Tuples If We Get This Error?

You might be thinking…

What is the point of using tuples if we get this error every time we try to update them?

Wouldn’t be a lot easier to always use lists instead?

We can see the fact that tuples are immutable as an added value for tuples when we have some data in our application that should never be modified.

Let’s say, for example, that our application integrates with an external system and it needs some configuration properties to connect to that system.

The tuple above contains two values: the API endpoint of the system we connect to and the port for their API.

We want to make sure this configuration is not modified by mistake in our application because it would break the integration with the external system.

So, if our code inadvertently updates one of the values, the following happens:

Remember, it’s not always good to have data structures you can update in your code whenever you want.

In this article we have seen when the error “tuple object does not support item assignment” occurs and how to avoid it.

You have learned how differently the tuple and list data types behave in Python and how you can use that in your programs.

If you have any questions feel free to post them in the comment below 🙂

Claudio Sabato is an IT expert with over 15 years of professional experience in Python programming, Linux Systems Administration, Bash programming, and IT Systems Design. He is a professional certified by the Linux Professional Institute .

With a Master’s degree in Computer Science, he has a strong foundation in Software Engineering and a passion for robotics with Raspberry Pi.

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Solve Python TypeError: 'tuple' object does not support item assignment

Consider the example below:

Solution #1: Change the tuple to list first

Solution #2: create a new tuple.

This tutorial shows you two easy solutions on how to change the tuple object element(s) and avoid the TypeError.

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Python typeerror: ‘tuple’ object does not support item assignment Solution

Tuples are immutable objects . “Immutable” means you cannot change the values inside a tuple. You can only remove them. If you try to assign a new value to an item in a variable, you’ll encounter the “typeerror: ‘tuple’ object does not support item assignment” error.

In this guide, we discuss what this error means and why you may experience it. We’ll walk through an example of this error so you can learn how to solve it in your code.

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Typeerror: ‘tuple’ object does not support item assignment.

While tuples and lists both store sequences of data, they have a few distinctions. Whereas you can change the values in a list, the values inside a tuple cannot be changed. Also, tuples are stored within parenthesis whereas lists are declared between square brackets.

Because you cannot change values in a tuple, item assignment does not work.

Consider the following code snippet:

This code snippet lets us change the first value in the “honor_roll” list to Holly. This works because lists are mutable. You can change their values. The same code does not work with data that is stored in a tuple.

An Example Scenario

Let’s build a program that tracks the courses offered by a high school. Students in their senior year are allowed to choose from a class but a few classes are being replaced.

Start by creating a collection of class names:

We’ve created a tuple that stores the names of each class being offered.

The science department has notified the school that psychology is no longer being offered due to a lack of numbers in the class. We’re going to replace psychology with philosophy as the philosophy class has just opened up a few spaces.

To do this, we use the assignment operator:

This code will replace the value at the index position 3 in our list of classes with “Philosophy”. Next, we print our list of classes to the console so that the user can see what classes are being actively offered:

Use a for loop to print out each class in our tuple to the console. Let’s run our code and see what happens:

Our code returns an error.

The Solution

We’ve tried to use the assignment operator to change a subject in our list. Tuples are immutable so we cannot change their values. This is why our code returns an error.

To solve this problem, we convert our “classes” tuple into a list . This will let us change the values in our sequence of class names.

Do this using the list() method:

We use the list() method to convert the value of “classes” to a list. We assign this new list to the variable “as_list”. Now that we have our list of classes stored as a list, we can change existing classes in the list.

Let’s run our code:

Our code successfully changes the “Psychology” class to “Philosophy”. Our code then prints out the list of classes to the console.

If we need to store our data as a tuple, we can always convert our list back to a tuple once we have changed the values we want to change. We can do this using the tuple() method:

This code converts “as_list” to a tuple and prints the value of our tuple to the console:

We could use this tuple later in our code if we needed our class names stored as a tuple.

The “typeerror: ‘tuple’ object does not support item assignment” error is raised when you try to change a value in a tuple using item assignment.

To solve this error, convert a tuple to a list before you change the values in a sequence. Optionally, you can then convert the list back to a tuple.

Now you’re ready to fix this error in your code like a pro !

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How to Solve ‘Tuple’ Object Does Not Support Item Assignment (Python)

Here’s everything about TypeError: ‘Tuple’ Object Does Not Support Item Assignment in Python.

You’ll learn:

• The specifics of the tuple data type
• The difference between immutable and mutable data types
• How to change immutable data types

So if you want to understand this error in Python and how to solve it, then you’re in the right place.

Let’s jump right in!

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Mutable, or Immutable? That Is the Question

Data types in Python are mutable or immutable .

All data types that are numeric , for example, are immutable . 

You can write something like this:

Have you changed the variable a ? 

Not really: When you write a = 1 , you put the object 1 in memory and told the name a to refer to this literal. 

Next, when you write a = a + 1 , Python evaluates the expression on the right:

Python takes the object referred by a (the 1 ) and then adds 1 to it. 

You get a new object, a 2 . This object goes right into the memory and a references instead of object 1 . 

The value of object 1 has not changed—it would be weird if 1 would out of a sudden a 2 , for example, wouldn’t it? So instead of overwriting an object ( 1 ), a new object ( 2 ) is created and assigned to the variable ( a ).

Mutable Data Types

More complex data types in Python are sequences such as: 

• Byte Arrays

Sequences contain several values, which can be accessed by index.

However, some sequences are mutable (byte arrays, lists) , while others are immutable (tuples) . 

You can create a tuple and access its elements like this:

Yet if you try to change one of the elements, you get an error:

Notice that the item in the tuple at index 2 is a list. You can change the list without changing the tuple:

The object stored in the tuple remains the same, but its contents have changed. But what if you still need to change the element in the tuple?

You can do this by converting the tuple to a list. Then you change the element, and then convert the list to a tuple again:

For large amounts of data, conversion operations can take quite a long time:

As you can see, for a list of 100 million float numbers, this operation takes about a second. This is not a long time for most tasks, but it is still worth considering if you are dealing with large amounts of data.

However, there is another way to “change” a tuple element—you can rebuild a tuple using slicing and concatenation:

Note that it is necessary to put a comma in parentheses to create a tuple of one element. If you use just parentheses, then (‘uno’) is not a tuple, but a string in parentheses . 

Concatenating a string with a tuple is not possible:

Interestingly, you can use shorthand operators on a tuple, like this:

Or even like this:

3 Examples of TypeError: ‘Tuple’ Object Does Not Support Item Assignment in Python

Let’s look at some practical examples of when this error can occur. The simplest is when you initially enter the sequence incorrectly:

In this example, the name list1 refers to a tuple despite the list in the name. The name does not affect the type of variable. To fix this error, simply change the parentheses to square brackets in the constructor:

Perhaps you have a list with some values, such as the student’s name and grade point average:

Alice did a poor job this semester, and her GPA dropped to 90:

Unfortunately, you cannot just change the average score in such a list. You already know that you can convert a tuple to a list, or form a new tuple. For example, like this:

However, if you need to change values regularly, it makes sense to switch from a list of tuples to a dictionary. Dictionaries are a perfect fit for such tasks. You can do this easily with the dict() constructor:

Now you can change the average by student name:

#1 Real World Example of TypeError: ‘Tuple’ Object Does Not Support Item Assignment in Python

An interesting example of a novice programmer trying to enter values in a list from the keyboard using the eval() function:

This method is not very reliable by itself.

Even if the user enters the correct sequence separated by commas—for example, 3, 2, 4, 1 —it will be evaluated in a tuple. 

Naturally, an attempt to assign a new value to a tuple element in the line list[i +1] = list[i] raises a TypeError: ‘tuple’ object does not support item assignment . 

Here, you see another mistake—which, by the way, may even be invisible during program execution. 

The my_sort function uses the list data type name as the argument name. This is not only the name of the data type, but also the list constructor. 

Python will not throw an error while executing this code, but if you try to create a list using the constructor inside the my_sort function, you will have big problems.

In this case, to enter elements into the list, it would be more correct to read the entire string and then split it using the split() method. If you need integer values, you can also apply the map() function, then convert the resulting map object into a list:

The construction looks a little cumbersome, but it does its job. You can also enter list items through a list comprehension:

You can choose the design that you like best.

#2 Real World Example of TypeError: ‘Tuple’ Object Does Not Support Item Assignment in Python

Another example of when a TypeError: ‘tuple’ object does not support item assignment may occur is the use of various libraries. 

If you have not studied the documentation well enough, you may not always clearly understand which data type will be returned in a given situation. In this example, the author tries to make the picture redder by adding 20 to the red color component:

This produces an error on the line pixel[0] = pixel[0] + 20 . How?

You are converting pixels to a list in line of code 3 . Indeed, if you check the type of the pixels variable, you get a list:

However, in the loop, you iterate over the pixels list elements, and they already have a different type. Check the type of the pixels list element with index 0 :

And this is a tuple!

So, you can solve this problem by converting lists to tuples inside a loop, for example.

However, in this case, you will need to slightly adjust the iterable value. This is because you will need the pixel color values and the index to write the new values into the original array. 

For this, use the enumerate() function:

The program will work successfully with that version of a loop, and you will get a redder image at the output. It would be more correct to trim values above 255 , for example:

But if the program consists only of this transformation, then Python will already truncate the values when saving the image.

Here’s more Python support:

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Python Tuple does not support item assignment

5 minute read

Introduction

In Python, tuples are immutable, meaning that their elements cannot be modified once they have been assigned. This means that attempting to assign a value to an element in a tuple will result in the following error:

TypeError: ‘tuple’ object does not support item assignment

This error can be frustrating, but there are a few ways to work around it and achieve the desired outcome. In this article, we will explore three different ways to fix this error and give an in-depth explanation of how each method works.

Error and Cause

When attempting to reassign an item in a tuple using the indexing operator, such as:

Python will raise a TypeError, indicating that the tuple object does not support item assignment. This is because, as previously mentioned, tuples are immutable , and their elements cannot be modified once they have been assigned.

Python’s tuple is a built-in data structure that can store multiple values in a single object. This makes it useful for situations where you need to store multiple related values together.

Tuples are defined by enclosing the values in parentheses and separating them with commas. For example, the following code creates a tuple with three integers:

This tuple object, as stated before, is immutable, which means that once it is created, its elements cannot be modified. This means that you cannot add, remove, or change the values of the elements in a tuple.

This is why when you try to reassign a value to an element in the tuple using the indexing operator, such as my_tuple[0] = 4, python will raise a TypeError, indicating that the tuple object does not support item assignment.

Fix 1: Convert Tuple to List

One way to fix this error is to convert the tuple to a list, make the desired changes, and then convert it back to a tuple.

In the above example, we first convert the tuple to a list using the built-in list() function. Once the tuple is converted to a list, we can use the indexing operator to reassign the value at index 0 to 4.

Since lists are mutable, this operation is allowed. Once the desired changes have been made, we convert the list back to a tuple using the built-in tuple() function. The original tuple object is now replaced by the new tuple object which has the desired value at index 0.

It’s important to note that the original tuple remains unchanged, and the new tuple is created with the modified values. This method is useful when you want to make changes to the tuple and need to keep the original tuple object intact.

Fix 2: Using Slicing

Another way to change the values in a tuple is by using slicing. You can create a new tuple with the desired values by slicing the original tuple and concatenating the new values.

In this example, we use slicing to create a new tuple. The my_tuple[:0] slice returns an empty tuple, the (4,) creates a new tuple with the value 4, and the my_tuple[1:] slice returns a new tuple with all elements of the original tuple except the first element.

We then concatenate these three tuples using the + operator to create a new tuple with the desired values.

It’s important to note that the original tuple remains unchanged, and the new tuple is created with the modified values.

This method is useful when you want to make changes to the tuple and need to keep the original tuple object intact.

It is also worth noting that this method is the most efficient one of the three, as it only uses slicing which has O(k) time complexity where k is the number of elements in the slice.

Fix 3: Creating a new Tuple

The last fix is creating a new tuple with the desired values.

This method works similarly to the previous method, but instead of using slicing and concatenation, we create a new tuple with the desired value and concatenate it with the rest of the elements of the original tuple using the + operator.

While tuples are immutable in Python, there are a few ways to work around the ‘tuple’ object does not support item assignment error. By converting the tuple to a list, using slicing, or creating a new tuple, you can achieve the desired outcome.

We hope this article was useful.

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How to Solve Python TypeError: ‘tuple’ object does not support item assignment

by Suf | Programming , Python , Tips

Tuples are immutable objects, which means you cannot change them once created. If you try to change a tuple in place using the indexing operator [], you will raise the TypeError: ‘tuple’ object does not support item assignment.

To solve this error, you can convert the tuple to a list, perform an index assignment then convert the list back to a tuple.

This tutorial will go through how to solve this error and solve it with the help of code examples.

Table of contents

Typeerror: ‘tuple’ object does not support item assignment.

Let’s break up the error message to understand what the error means. TypeError occurs whenever you attempt to use an illegal operation for a specific data type.

The part 'tuple' object tells us that the error concerns an illegal operation for tuples.

The part does not support item assignment tells us that item assignment is the illegal operation we are attempting.

Tuples are immutable objects, which means we cannot change them once created. We have to convert the tuple to a list, a mutable data type suitable for item assignment.

Let’s look at an example of assigning items to a list. We will iterate over a list and check if each item is even. If the number is even, we will assign the square of that number in place at that index position.

Let’s run the code to see the result:

We can successfully do item assignments on a list.

Let’s see what happens when we try to change a tuple using item assignment:

We throw the TypeError because the tuple object is immutable.

To solve this error, we need to convert the tuple to a list then perform the item assignment. We will then convert the list back to a tuple. However, you can leave the object as a list if you do not need a tuple.

Let’s run the code to see the updated tuple:

Congratulations on reading to the end of this tutorial. The TypeError: ‘tuple’ object does not support item assignment occurs when you try to change a tuple in-place using the indexing operator [] . You cannot modify a tuple once you create it. To solve this error, you need to convert the tuple to a list, update it, then convert it back to a tuple.

For further reading on TypeErrors, go to the article:

• How to Solve Python TypeError: ‘str’ object does not support item assignment

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How to Fix “TypeError: Tuple Does Not Support Item Assignment” in Python?

Did you assign a tuple to a new value and get the TypeError: tuple does not support item assignment in Python?

If you’re working with Python and you encounter the “TypeError: ‘tuple’ does not support item assignment” error, it means that you are trying to change the value of an element within a tuple, which is not possible.

When we try to update the value of an item in a tuple, Python throws the error TypeError: ‘tuple’ object does not support item assignment . Tuples are immutable data types, hence assigning a tuple to a variable or data causes the TypeError exception . Transforming tuples to lists or slicing them, can be helpful in preventing the TypeError: ‘tuple’ object does not support item assignment .

Furthermore, you can convert the tuple to a list, to make the necessary changes, and then convert the list back to a tuple to fix the problem. 

In this article, we’ll discuss the TypeError: tuple object does not support item assignment in Python, why it occurs, and how to fix ⚒️it. So without further ado, let’s dive deep into the topic. Let’s go over a few examples that will show this error’s causes and possible solutions.

Table of Contents

Why does the typeerror:  tuple does not support item assignment error occur, how to fix typeerror: ‘tuple’ object does not support item assignment in python, 1. assigning a value to the index, 2. with the use of slice operator, 3. apply list inside a tuple.

As we’ve discussed in Python, when we try to assign a new value to a tuple that causes TypeError:  tuple object does not support item assignment. Let’s see an example 👇

See the above example; we have created a tuple Tuple_1 and assigned values. Then we assigned “Kelvin” at index 2 of Tuple and print the tuple that gives the TypeError:  tuple does not support item assignment as we are trying to assign a value to an already created tuple.

As we have seen in the above example, we have created a tuple and assigned a value, we can convert the tuple into a list, and then we can assign values to it. To convert a tuple into a list, we utilized the list() class. In the above example, we have assigned 1. 

To fix the error first we have to change the tuple to a list: we have three different alternate solutions.

• Assigning a Value to the Index
• With the Use of Slice Operator
• Apply List Inside a Tuple

We have to convert Convert the tuple into a list by using a list function and then assigning a value at any index of a list that will update any elements in the list. The final step is to convert 

final list back to a tuple as shown in the following example.

In the above example, we have converted the tuple to a list, assigned “Sofia” at the index on the list, and again converted the list to a tuple and printed it.

This “Type error: tuple object does not support item assignment” can also be avoided using the slicing operator. Let’s look at how we can slice our original tuple to get a new one after omitting some elements of the tuple. You can also add an element to any index after in  the tuple using the slice operator.

If one element in a tuple is listed, only on that particular index we can assign another element. But if we assign an element at the index of an element that is not a list it will generate a “Type error: tuple object does not support item assignment.” Let’s see what happens when a tuple has a list as one of its elements.

To summarize the article on how to fix the TypeError: tuple does not support item assignment , we’ve discussed why it occurs and how to fix it. Furthermore, we’ve seen that the three approaches that help fix the TypeError: ‘tuple’ object do not support item assignment , including Assigning a value to the index, With the use of slice Operator, Applying a list inside a tuple

Let’s have a quick recap of the topics discussed in this article.

• Why does the TypeError: ‘tuple’ object does not support item assignment occurs?
• How to fix the TypeError TypeError: tuple does not support item assignment in Python?
• Assigning a value to the index.
• With the use of slice Operator.
• Apply List inside a Tuple.

If you’ve found this article helpful, don’t forget to share and comment below 👇 which solutions have helped you solve the problem.

Happy Coding!

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TypeError: ‘tuple’ object does not support item assignment

In Python, tuples are immutable, and elements stored inside the tuple will not be modified, unlike a list. The list is mutable, and the element value of the list is easily modified after its creation. The “tuple object does not support item assignment” TypeError is invoked in the program when the item value of the tuple is changed.

This Python write-up will cover the following contents and discuss various reasons and solutions for “TypeError: tuple object does not support item assignment” with numerous examples:

Reason: Changing Tuple Item Value

Solution 1: convert tuple into a list, solution 2: declare list instead of tuple.

The prominent reason that invokes the error “ tuple object does not support item assignment ” is when the user tries to modify the item value of the tuple in a Python program.

The above snippet shows the TypeError when the tuple value is changed.

To resolve “TypeError”, the tuple value is converted into a list value using the built-in “list()” function. The list is mutable, unlike a tuple. So, the element value is easily replaced by accessing the index number.

In the above code, the tuple is first converted into a list, and after that, the element of the list is changed using an index. After successfully changing the list element, the updated value has been converted back to a tuple.

The tuple’s new item value, “ Zach ”, has been replaced by the old value, “ Binny ”, in the above output.

The very efficient way to handle this error is using list data type for storing multiple values instead of tuples at the start of the program. Because using a list data type allows the user to change the element value at any time in the program.

In the above code, the “ list_value ” is initialized and the element of the list is replaced by accessing the index.

Note: If you want your answer in a tuple, then the “tuple()” function is utilized in the program to convert the list into a tuple.

The above output shows the original list and the updated list.

That’s it from this guide!

In Python, the “ tuple object does not support item assignment ” error arises when the user tries to change a tuple’s element/item value. To resolve this “TypeError”, the tuple value is converted into a list using the “list()” function, and the item’s value is changed using the specific index. After changing the items on the list, you may convert the list back into tuples. This post presented various reasons and solutions for the “tuple object does not support item assignment” TypeError in Python.

Python TypeError: 'tuple' object does not support item assignment Solution

Posted in PROGRAMMING LANGUAGE /   PYTHON

Vinay Khatri Last updated on June 27, 2024

Table of Content

In Python, we have a built-in data structure " tuple " which is similar to a Python list and stores elements in sequential order. The only difference between a Python list and a tuple is that the tuple is an immutable data structure, which means once a tuple object is defined, we can not change its elements. If we try to change the tuple elements using indexing and assignment operator, we will receive the TypeError: 'tuple' object does not support item assignment Error.

In this Python guide, we will discuss this error in detail and learn how to debug it. We will also walk through a common example to demonstrate this error. So without further ado, let's get started with the Error statement.

Python Error: TypeError: 'tuple' object does not support item assignment

The Error Statement TypeError: 'tuple' object does not support item assignment is divided into two parts Exception Type and Error Message.

• TypeError (Exception Type)
• 'tuple' object does not support item assignment (Error Message)

1. TypeError

TypeError is a standard Python exception. It is raised in a Python program when we try to perform an invalid or unsupported operation on a Python object.

2. 'tuple' object does not support item assignment

This error message tells us that the tuple object does not support new value assignment to its elements. You will only encounter this error message when you try to change the values of a tuple element using indexing.

Although we can use indexing to access the individual tuple elements, we can not use indexing to change tuple element values.

Here we are getting this error because in line 5, we are trying to assign a new value to the tuple " letters ". As tuple does not support element change operation, it throws the error when we try to assign a new value to the tuple element. Now let's discuss a common scenario example, and in the solution, we will see an alternative way to debug this problem and add and change the value of a tuple element using some logic.

Common Example Scenario

Tuples are faster as compared to the Python list. That's why many Python developers use tuples to store items or element values. Although tuple supports element access using indexing, it throws an error when changing its elements. This is also one of the main reasons why many pythoneer use tuples instead of lists when they do not want to change the elements of the container throughout the program.

But let's say you come across a situation when you want to change the element value of a tuple, then what would you do?

Here we will discuss an example where we first try to change one of the values of a tuple using indexing. Then in the solution, we will discuss how we can achieve it.

Break the code

The error statement is quite expected. We know that when we try to change the tuple element value using indexing, we get the error. In line 5, we tried to change the first element of the tuple " sem_1_subjects " from "Java" to "Python" , which is the cause of this error statement.

When we use the tuple element as a container to store elements, we think of that container as intact throughout the program. But in the case when we come across a situation where we need to change the value of the tuple elements, there we first need to convert that tuple object to a list using list() function. Then only we can change its values. After changing the value, we can convert back the list object to the tuple using tuple() function.

Example solution

In this Python tutorial, we discussed the "TypeError: 'tuple' object does not support item assignment" Error in detail. This error raises in a Python program when we try to change the value of a tuple element using the assignment operator. A tuple is an immutable data structure, and once we define all its elements, we can not change them. To change its elements, first, need to convert the tuple object to a list, and then only we can change its values.

If you are still getting this error in your Python program, you can share your code in the comment section. We will try to help you in debugging.

People are also reading:

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Vinay Khatri I am a Full Stack Developer with a Bachelor's Degree in Computer Science, who also loves to write technical articles that can help fellow developers.

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TypeError: ‘tuple’ object does not support item assignment ( Solved )

Tuples, lists, maps are data structures in python. All of them are used for creating multiple items in a single variable. But they have different features. Some support item assignment and some not. In this entire tutorial you will know how to solve the TypeError ‘tuple’ object does not support item assignment.

What are tuples ?

The syntax for the list is the below.

What cause ‘tuple’ object does not support item assignment error

Suppose I have tuple with name of the three students in it. I want to change the name of the third student. And if I use the below lines of code then I will get the ‘tuple’ object does not support item assignment error.

Solution for ‘tuple’ object does not support item assignment error

Execute the below lines of code to change the element of the tuple.

If you have any query then you can contact us for more help.

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Typeerror: ‘tuple’ object does not support item assignment

One of the errors we encounter, when we try to change the value of tuple item, is Typeerror: ‘tuple’ object does not support item assignment .

Furthermore in this guide, we will tackle why this error occurs, as well as practical example codes for better understanding.

What is Typeerror: ‘tuple’ object does not support item assignment?

The “TypeError: ‘tuple’ object does not support item assignment” occurs when we attempt to change the value of an item in a tuple.

To solve the error, convert the tuple to a list, change the item at the specific index, and convert the list back to a tuple.

Why Typeerror: ‘tuple’ object does not support item assignment?

Every time we try to modify or assign a value to an element within a tuple using the assignment operator…

Essentially we are trying to change the content of an immutable object, which is not possible in Python.

Now that we understand what is this error and why this error occurs, let’s proceed to solutions to this error.

How to fix Typeerror: ‘tuple’ object does not support item assignment

Here are three possible solutions with example codes and their explanations.

Solution 1: Convert the tuple to a list and back to a tuple

One way to fix the error is to convert the tuple to a list, make the needed modifications, and then convert it back to a tuple.

Solution 2: Use tuple concatenation to create a new tuple

Here is an example code:

We then create a new tuple called new_tuple that contains the first and third elements of my_tuple and a modified value for the second element.

Solution 3: Use named tuples from the collections module

A third way to fix the error is to use named tuples from the collections module.

Thus, when you need to keep track of the meaning of each element.

Any of the approaches can fix the error depending on your error.

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ArcPy Update Cursor after nested Search Cursor giving tuple assignment error?

I am running ArcMap 10.4.1. I am running a script that uses a DA search cursor nested inside an update cursor to assign variables from values in a table. The script then writes those same variables to a feature class in the update cursor. I have done this many times in the past, but now I am getting a tuple assignment error when I try to assign row values in the update cursor. I know tuples aren't mutable and I am not trying to assign values in the search cursor. What is the problem here? This syntax has worked many times in the past.

The script fails on the first attempted row assignment after the search cursor:

row[2] = tblAppAdd TypeError: 'tuple' object does not support item assignment

Here is the script portion (edited for length):

• arcgis-10.4

• 2 Try calling your SearchCursor iterator something like sRow since you're already using row for the UpdateCursor. –  Evan Commented Oct 25, 2016 at 20:25
• 5 Nested cursors are generally frowned upon. The typical approach is to use a search cursor first to create a dictionary of the key/value pairs you need (in your case from tblPatients), then reference the dictionary from within the update cursor. –  Bjorn Commented Oct 25, 2016 at 20:41

First, you reassigned row. Change row to srow for the search cursor and row to urow for the update cursor.

The error you're getting is that you're trying to update the search cursor object (since it got reassigned). The arcpy.da.search cursor returns a tuple, and update cursor returns a list.

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TypeError: 'tuple' object does not support item assignment

Updated May 03, 2020

In this article, we will learn about the error TypeError: "tuple" object does not support item assignment . A tuple is a collection of ordered and unchangeable items as they are immutable . So once if a tuple is created we can neither change nor add new values to it.

The error “ TypeError: ‘tuple’ object does not support item assignment ” generates when we try to assign a new value in the tuple.

Let us understand it more with the help of an example.

In the above example in line 4 of the code, we are trying to assign a new value at index 2. Thus raising the error TypeError: 'tuple' object does not support item assignment .

To assign a new value in a tuple we can convert the tuple into a list, then after assigning convert the list back to the tuple as shown in the example below. Though it is recommended not to do so.

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How to Fix “TypeError: unsupported operand type(s) for +: ‘NoneType’ and ‘str'” in Python

The TypeError: unsupported operand type(s) for +: ‘NoneType’ and ‘str’ error in Python occurs when attempting to concatenate a NoneType object with the string. This is a common error that arises due to the uninitialized variables missing the return values or improper data handling. This article will explore the causes of this error and provide strategies for fixing it.

Understanding the Error

In Python , NoneType is the type of the None object which represents the absence of the value. When you attempt to concatenate None with the string using the + operator Python raises a TypeError because it does not know how to handle the operation between these incompatible types.

Problem Statement

In Python, consider the scenario where we have code like this:

When executing this code we may encounter the following error:

Approach to Solving the Problem

To resolve the “TypeError: unsupported operand type(s) for +: ‘NoneType’ and ‘str'” error we need to the ensure that your variables are of the expected types before performing the operations such as the string concatenation. This involves:

• Checking for NoneType: Ensure that functions or operations that can return None are handled properly before using their results.
• Error Handling: Implement appropriate error handling to the gracefully manage scenarios where None might be encountered unexpectedly.

Different Solutions to Fix the Error

1. check for uninitialized variables.

Ensure that all variables are properly initialized before use.

2. Verify Function Return Values

The Ensure that functions return the expected type and handle cases where a function might return the None.

3. Use Default Values in Conditional Statements

Provide the default values for the variables that might not be initialized under certain conditions.

3. Use String Formatting

Python offers several ways to format strings that can handle NoneType gracefully. These include the format() method, f-strings (Python 3.6+), and the % operator.

Using format()

Using f-strings, using % operator, 4. handle nonetype with a function.

You can create a utility function to handle the concatenation, checking for None values and replacing them with a default value.

Let’s walk through the more detailed example that demonstrates identifying and fixing this error.

The TypeError: unsupported operand type(s) for +: ‘NoneType’ and ‘str’ error in Python is a common issue caused by the attempting to the concatenate None with the string. By initializing variables properly verifying the function return values using the default values in the conditionals and leveraging string formatting methods we can avoid this error. Always ensure the code handles NoneType objects appropriately to maintain robustness and prevent runtime errors.

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How can I fix the error “numpy.float64′ object does not support item assignment”?

Table of Contents

The error “numpy.float64′ object does not support item assignment” occurs when attempting to assign a value to an individual element in a NumPy array that has been defined as a float64 data type. To fix this error, you can either change the data type of the array to one that supports item assignment, such as a list, or use the appropriate NumPy function to modify the array’s elements without assigning them directly.

Fix: ‘numpy.float64’ object does not support item assignment

One common error you may encounter when using Python is:

This error usually occurs when you attempt to use brackets to assign a new value to a NumPy variable that has a type of float64 .

The following example shows how to resolve this error in practice.

How to Reproduce the Error

Suppose we create some NumPy variable that has a value of 15.22 and we attempt to use brackets to assign it a new value of 13.7 :

We receive the error that ‘numpy.float64’ object does not support item assignment .

We received this error because one_float is a scalar but we attempted to treat it like an array where we could use brackets to change the value in index position 0.

Since one_float is not an array, we can’t use brackets when attempting to change its value.

How to Fix the Error

The way to resolve this error is to simply not use brackets when assigning a new value to the float:

We’re able to successfully change the value from 15.22 to 13.7 because we didn’t use brackets.

Note that it’s fine to use brackets to change values in specific index positions as long as you’re working with an array.

For example, the following code shows how to change the first element in a NumPy array from 15.22 to 13.7 by using bracket notation:

Additional Resources

The following tutorials explain how to fix other common errors in Python:

Related terms:

• Why does a ‘numpy.float64’ object return an error stating that it is not iterable in the context of fixing it?
• Why am I receiving a TypeError stating that a ‘numpy.float64’ object is not callable when trying to use the Fix function?
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3. Un’introduzione informale a Python ¶

Nei seguenti esempi, input e output si distinguono per la presenza o meno del prompt ( >>> e … ): per ripetere l’esempio, è necessario digitare tutto dopo il prompt, quando questo è presente; le righe che non iniziano con un prompt vengono emesse dall’interprete. Si noti che un prompt secondario su una linea da solo in un esempio significa che è necessario digitare una riga vuota; questo viene utilizzato per terminare un comando a più righe.

Puoi attivare o disattivare la visualizzazione dei prompt e dell’output facendo clic su >>> nell’angolo in alto a destra di un riquadro di esempio. Se nascondi i prompt e l’output di un esempio, potrai copiare e incollare facilmente le righe di input nel tuo interprete.

Molti degli esempi di questo manuale, anche quelli inseriti al prompt interattivo, includono commenti. I commenti in Python iniziano con il carattere hash , # , e si estendono fino alla fine della riga. Un commento può apparire all’inizio di una riga o dopo uno spazio bianco o codice, ma non all’interno di una stringa. Un carattere hash all’interno di una stringa letterale è solo un carattere. Poiché i commenti servono solo a chiarire il codice e non sono interpretati da Python, possono essere omessi quando si scrivono gli esempi.

Alcuni esempi:

3.1. Usare Python come calcolatrice ¶

Proviamo con alcuni semplici comandi di Python. Avviare l’interprete e attendere il prompt primario, >>> . (Non dovrebbe volerci molto.)

3.1.1. Numeri ¶

L’interprete agisce come una semplice calcolatrice: è possibile digitare un’espressione per scrivere il valore. La sintassi dell’espressione è semplice: gli operatori + , - , * e / funzionano come nella maggior parte degli altri linguaggi (per esempio, Pascal o C); le parentesi ( () ) possono essere utilizzate per il raggruppamento. Per esempio:

I numeri interi (es. 2 , 4 , 20 ) hanno tipo int , quelli in virgola mobile (es. 5.0 , 1.6 ) hanno tipo float . Torneremo a parlare ancora dei tipi numerici più avanti nel tutorial.

La divisione ( / ) restituisce sempre un float. Per fare floor division e ottenere un risultato intero (scartando qualsiasi cifra decimale) si può usare l’operatore // ; per calcolare il resto si può usare % :

Con Python, è possibile utilizzare l’operatore ** per calcolare le potenze [ 1 ] :

Il segno uguale ( = ) è usato per assegnare un valore ad una variabile. Successivamente, nessun risultato viene visualizzato prima della successiva richiesta:

Se una variabile non è stata ”definita» (a cui è stato assegnato un valore), usarla vi darà un errore:

C’è pieno supporto per i numeri in virgola mobile; gli operatori con operandi di tipo misto convertono l’intero in un numero in virgola mobile:

In modalità interattiva, l’ultima espressione stampata viene assegnata alla variabile _ . Questo significa che quando si utilizza Python come calcolatrice da tavolo, è un po” più facile continuare i calcoli, ad esempio:

Questa variabile deve essere trattata dall’utente in sola lettura. Non va assegnato esplicitamente un valore ad essa — si dovrebbe invece creare una variabile locale indipendente con lo stesso nome, mascherando così la variabile built-in e il suo comportamento magico.

Oltre a int e float , Python supporta altri tipi di numeri, come Decimal e Fraction . Python ha anche il supporto incorporato per complex numbers , e usa il suffisso j o J per indicare la parte immaginaria (es. 3+5j ).

3.1.2. Testo ¶

Python può manipolare testo (rappresentato dal tipo str , le cosiddette «stringhe») così come numeri. Questo include caratteri « ! », parole « rabbit », nomi « Paris », frasi « Got your back. », ecc. « Yay! :) ». Possono essere racchiusi tra virgolette singole ( '...' ) o virgolette doppie ( "..." ) con lo stesso risultato [ 2 ] .

racchiudere una virgoletta dello stesso tipo, dobbiamo farne l“«escape», precedendola con \ . In alternativa, possiamo usare l’altro tipo di virgolette:

Nella shell di Python, la definizione di una stringa e la stringa di output possono apparire differenti. La funzione print() produce un output più leggibile, omettendo le virgolette di chiusura e stampando i caratteri con escape e speciali:

Se non si desidera che i caratteri preceduti da \ siano interpretati come caratteri speciali, è possibile utilizzare le cosiddette raw strings aggiungendo un r prima del primo apice:

C’è un aspetto sottile nelle stringhe raw: una stringa raw non può terminare con un numero dispari di caratteri \ ; vedi la voce FAQ per ulteriori informazioni e soluzioni.

Le lettere letterali delle stringhe possono estendersi su più linee. Un modo è quello di usare gli apici tripli: """...""" o '''...''' . La fine delle linee sono automaticamente incluse nella stringa, ma è possibile evitare che ciò avvenga aggiungendo un \ alla fine della linea. Il seguente esempio:

produce il seguente output (si noti che la nuova linea iniziale non è inclusa):

Le stringhe possono essere concatenate (incollate insieme) con l’operatore + e ripetute con * :

Due o più letterali di tipo stringa (cioè quelli racchiusi tra virgolette) posizionati uno accanto all’altro sono automaticamente concatenati.

Questa funzione è particolarmente utile quando si vogliono separare stringhe lunghe:

Questo funziona solo con due letterali, ma non con variabili o expression :

Se volete concatenare variabili o una variabile e un letterale, usate + :

Le stringhe possono essere indicizzate (sottoscritte), e il primo carattere ha indice 0. Non esiste un tipo carattere specifico; un carattere è semplicemente una stringa di dimensione uno:

Gli indici possono anche essere numeri negativi, per iniziare a contare da destra:

N.B. Poiché -0 è uguale a 0, gli indici negativi partono da -1.

Oltre all’indicizzazione, è supportato anche lo slicing . Mentre l’indicizzazione è usata per ottenere i singoli caratteri, lo slicing permette di ottenere una sottostringa:

Nello slice gli indici hanno degli utili valori predefiniti; un primo indice omesso è zero, un secondo indice omesso è uguale alla dimensione della stringa che si sta tagliando:

Si noti come l’inizio sia sempre incluso, e la fine sempre esclusa. Questo fa sì che s[:i] + s[i:] è sempre uguale a s :

Un modo per ricordare come funzionano le fette è quello di pensare agli indici come al punto tra caratteri, con il bordo sinistro del primo carattere numerato 0. Poi il bordo destro dell’ultimo carattere di una stringa di caratteri n ha l’indice n , per esempio:

La prima riga di numeri dà la posizione degli indici 0…6 nella stringa; la seconda riga dà i corrispondenti indici negativi. La porzione da i a j è costituita da tutti i caratteri tra i bordi contrassegnati rispettivamente con i e j .

Per gli indici non negativi, la lunghezza di una fetta è la differenza degli indici, se entrambi sono entro i limiti. Per esempio, la lunghezza di word[1:3] è 2.

Il tentativo di utilizzare un indice troppo grande comporta un errore:

Tuttavia, gli indici delle sottostringhe fuori range (che superano la lunghezza della stringa) sono gestiti a modo quando vengono utilizzati per l’affettamento:

Le stringhe Python non possono essere modificate — sono immutable . Pertanto, l’assegnazione di una posizione indicizzata nella stringa comporta un errore:

Se avete bisogno di una stringa diversa, dovreste crearne una nuova:

La funzione integrata len() restituisce la lunghezza di una stringa:

Le stringhe sono esempi di tipi di sequenze , e supportano le operazioni comuni supportate da questi tipi di dato.

Un gran numero di metodi per le trasformazioni di base e la ricerca sono supportati dalle stringhe.

Stringhe con expression incorporate.

Informazioni sulla formattazione delle stringhe con str.format() .

Il vecchio metodo di formattazione, quello che prevede un template a sinistra dell’operatore % è descritto più dettagliatamente qui.

3.1.3. Liste ¶

Python conosce un certo numero di tipi di dati composti , usati per raggruppare altri valori. La più versatile è la lista , che può essere scritta come una lista di valori separati da virgola (elementi) tra parentesi quadre. Gli elenchi possono contenere elementi di tipo diverso, ma di solito gli elementi hanno tutti lo stesso tipo.

Come le stringhe (e tutti gli altri tipi built-in sequence ), le liste possono essere indicizzate e tagliate:

Gli elenchi supportano anche operazioni come la concatenazione:

A differenza delle stringhe, che sono immutable , le liste sono di tipo mutable , cioè è possibile modificarne il contenuto:

Potete anche aggiungere nuovi elementi alla fine della lista, usando il metodo list.append() (vedremo di più riguardo i metodi più avanti):

L’assegnazione semplice in Python non copia mai i dati. Quando assegni una lista a una variabile, la variabile si riferisce alla lista esistente . Qualsiasi modifica apportata alla lista tramite una variabile sarà visibile attraverso tutte le altre variabili che si riferiscono ad essa.:

Tutte le operazioni di taglio restituiscono una nuova lista contenente gli elementi richiesti. Ciò significa che la seguente sezione restituisce una nuova shallow copy della list:

L’assegnazione a uno slice è anche possibile, per cambiare anche la dimensione della lista o cancellarne gli elementi completamente:

La funzione len() si applica anche alle liste:

E” possibile nidificare liste (creare liste contenenti altre liste), ad esempio:

3.2. Primi passi di programmazione ¶

Naturalmente, possiamo usare Python per compiti più complicati che sommare insieme due più due. Per esempio, possiamo scrivere una prima sottosequenza della Successione di Fibonacci come segue:

Questo esempio introduce diverse nuove funzionalità.

La prima riga contiene una assegnazione multipla : le variabili a e b ottengono simultaneamente i nuovi valori 0 e 1. Sull’ultima riga viene usata di nuovo, dimostrando che le espressioni sul lato destro sono tutte valutate prima di una qualsiasi delle assegnazioni. Le espressioni del lato destro sono valutate da sinistra a destra.

Il ciclo while viene eseguito finché la condizione (qui: a < 10 ) rimane vera. In Python, come in C, qualsiasi valore intero diverso da zero è vero; zero è falso. La condizione può anche essere una stringa o un valore di lista, infatti qualsiasi sequenza; qualsiasi cosa con una lunghezza diversa da zero è vera, le sequenze vuote sono false. Il test utilizzato nell’esempio è un semplice confronto. Gli operatori di confronto standard sono scritti come in C: < (minore di), > (maggiore di), == (uguale a), <= (minore o uguale a), >= (maggiore o uguale a) e != (diverso da).

Il corpo del ciclo è indentato : l’indentazione è il modo di Python di raggruppare le istruzioni. Al prompt interattivo, è necessario digitare un tab o spazio/i per ogni riga rientrata. In pratica si prepara un input più complicato per Python con un editor di testo; tutti gli editor di testo seri hanno una funzione di auto-indentazione. Quando un’istruzione composta è inserita nella shell interattiva, deve essere seguita da una riga vuota per indicare il completamento (poiché l’analizzatore non può indovinare quando si è digitata l’ultima riga). Si noti che ogni riga all’interno di un blocco di base deve essere rientrata della stessa quantità.

La funzione print() scrive il valore dell’argomento o degli argomenti che le vengono passati. Si differenzia dal solo scrivere l’espressione che si vuole scrivere (come abbiamo fatto in precedenza negli esempi della calcolatrice) per il modo in cui gestisce argomenti multipli, numeri in virgola mobile e stringhe. Le stringhe vengono stampate senza virgolette e viene inserito uno spazio tra gli elementi, in modo da poter formattare bene le cose, in questo modo:

L’argomento end può essere usato per evitare la nuova linea dopo l’output, o terminare l’output con una stringa diversa:

Table of Contents

• 3.1.1. Numeri
• 3.1.2. Testo
• 3.1.3. Liste
• 3.2. Primi passi di programmazione

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'tuple' object does not support item assignment - DataFrame

I have a dictionary d of data frames, where the keys are the names and the values are the actual data frames. I have a function that normalizes some of the data frame and spits out a plot, with the title. The function takes in a tuple from d.items() (as the parameter df ) so the first (0th) element is the name and the next is the data frame.

I have to do some manipulations on the data frame in the function, and I do so using df[1] without any issues. However, one line is df[1] = df[1].round(2) and this throws the error 'tuple' object does not support item assignment . I have verified that df[1] is a data frame by printing out its type write before this line. Why doesn't this work? It's not a tuple.

• 1 Show the sample code please to reproduce this problem –  MohitC Commented Apr 27, 2020 at 14:29

That's because your variable is a tuple and you can't assign to a tuple. Tuples are immutable. My understanding of your question:

Notice that "i" is a tuple, because that is what .items() returns (tuples). You can't save to i, even if what you are overwriting is something that is mutable. I know that this sounds strange, because you can do things like this:

The reason this works is complicated. Essentially the tuples above are storing the pointers to the information within the tuples (not the data themselves). Hence, if you access a tuple's item (like x[1]), then python takes you to that pointers item (in my case a list) and allows you to run append on it, because the list is mutable. In your case, you are not trying to access the i[1] all by itself, you are trying to overwrite the i[1] entry in the tuple. Hope this makes sense.

• But I printed out the type of df[1] write before the line. It is a DataFrame. df is a tuple, df[0] is the name, df[1] is the dataframe. –  formicaman Commented Apr 27, 2020 at 14:52
• 1 Right. Just like if I printed x[1] it would be a list. But I still can't save to x[1], because that would be saving to the tuple x. I can update x[1] with something like append, but I can't save to x[1]. I can pull the list out of the tuple, like y = x[1]. Now y is not in the tuple, so now I can run " y = y + [1] " and overwrite y, because I am not saving to the tuple. –  Bobby Ocean Commented Apr 27, 2020 at 14:55

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