Typeerror list indices must be integers or slices not tuple как исправить

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In Python, we index lists with numbers. To access an item from a list, you must refer to its index position using square brackets []. Using a tuple instead of a number as a list index value will raise the error “TypeError: list indices must be integers, not tuple”.

This tutorial will go through the error and an example scenario to learn how to solve it.

TypeError: list indices must be integers, not tuple 

What is a TypeError?

TypeError tells us that we are trying to perform an illegal operation on a Python data object.

Indexing a List

Indexing a list starts from the value 0 and increments by 1 for each subsequent element in the list. Let’s consider a list of pizzas:

pizza_list = ["margherita", "pepperoni", "four cheeses", "ham and pineapple"]

The list has four values. The string “margherita” has an index value of 0, and “pepperoni” has 1. To access items from the list, we need to reference these index values.

print(pizza_list[2])

four cheeses

Our code returns “four cheeses“.

In Python, TypeError occurs when we do an illegal operation for a specific data type.

Tuples are ordered, indexed collections of data. We cannot use a tuple value to access an item from a list because tuples do not correspond to any index value in a list.

You may encounter a similar TypeError to this one called TypeError: list indices must be integers or slices, not str, which occurs when you try to access a list using a string.

The most common sources of this error are defining a list of lists without comma separators and using a comma instead of a colon when slicing a list.

Example #1: List of Lists with no Comma Separator

Let’s explore the error further by writing a program that stores multiples of integers. We will start by defining a list of which stores lists of multiples for the numbers two and three.

multiples = [

    [2, 4, 6, 8, 10]

    [3, 6, 9, 12, 15]

]

We can ask a user to add the first five of multiples of the number four using the input() function:

first = int(input("Enter first multiple of 4"))

second = int(input("Enter second multiple of 4"))

third = int(input("Enter third multiple of 4"))

fourth = int(input("Enter fourth multiple of 4"))

fifth = int(input("Enter fifth multiple of 4"))

Once we have the data from the user, we can append this to our list of multiples by enclosing the values in square brackets and using the append() method.

multiples.append([first, second, third, fourth, fifth])

print(multiples)

If we run this code, we will get the error.”

TypeError                                 Traceback (most recent call last)
      1 multiples = [
      2 [2, 4, 6, 8, 10]
      3 [3, 6, 9, 12, 15]
      4 ]

TypeError: list indices must be integers or slices, not tuple

The error occurs because there are no commas between the values in the multiples list. Without commas, Python interprets the second list as the index value for the first list, or:

# List           Index

[2, 4, 6, 8, 10][3, 6, 9, 12, 15]

The second list cannot be an index value for the first list because index values can only be integers. Python interprets the second list as a tuple with multiple comma-separated values.

Solution

To solve this problem, we must separate the lists in our multiples list using a comma:

multiples = [

[2, 4, 6, 8, 10],

[3, 6, 9, 12, 15]

]

first = int(input("Enter first multiple of 4:"))

second = int(input("Enter second multiple of 4:"))

third = int(input("Enter third multiple of 4:"))

fourth = int(input("Enter fourth multiple of 4:"))

fifth = int(input("Enter fifth multiple of 4:"))

multiples.append([first, second, third, fourth, fifth])

print(multiples)

If we run the above code, we will get the following output:

Enter first multiple of 4:4

Enter second multiple of 4:8

Enter third multiple of 4:12

Enter fourth multiple of 4:16

Enter fifth multiple of 4:20

[[2, 4, 6, 8, 10], [3, 6, 9, 12, 15], [4, 8, 12, 16, 20]]

The code runs successfully. First, the user inputs the first five multiples of four, the program stores that information in a list and appends it to the existing list of multiples. Finally, the code prints out the list of multiples with the new record at the end of the list.

Example #2: Not Using a Colon When Slicing a List

Let’s consider the list of multiples from the previous example. We can use indexing to get the first list in the multiples list.

first_set_of_multiples = multiples[0]

print(first_set_of_multiples)

Running this code will give us the first five multiples of the number two.

[2, 4, 6, 8, 10]

Let’s try to get the first three multiples of two from this list:

print(first_set_of_multiples[0,3])

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
1 print(first_set_of_multiples[0,3])

TypeError: list indices must be integers or slices, not tuple

The code fails because we pass [0,3] as the index value. Python only accepts integers as indices for lists.

Solution

To solve this problem and access multiple elements from a list, we need to use the correct syntax for slicing. We must use a colon instead of a comma to specify the index values we select.

print(first_set_of_multiples[0:3])

[2, 4, 6]

The code runs successfully, and we get the first three multiples of the number two printed to the console.

Note that when slicing, the last element we access has an index value one less than the index to the right of the colon. We specify 3, and the slice takes elements from 0 to 2. To learn more about slicing, go to the article titled “How to Get a Substring From a String in Python“.

Summary

Congratulations on reading to the end of this tutorial. The Python error “TypeError: list indices must be integers, not tuple” occurs when you specify a tuple value as an index value for a list. This error commonly happens if you define a list of lists without using commas to separate the lists or use a comma instead of a colon when taking a slice from a list. To solve this error, make sure that when you define a list of lists, you separate the lists with commas, and when slicing, ensure you use a colon between the start and end index.

For further reading on the list and tuple data types, go to the article: What is the Difference Between List and Tuple in Python?

Go to the online courses page on Python to learn more about Python for data science and machine learning.

Have fun and happy researching!

Are you looking for a way to fix “TypeError: list indices must be integers or slices not tuple” error?

Python TypeError is the exception that indicates the invalid usage of an object type in an operation. The error usually occurs if an operation is performed on an object that does not support the operation itself, or an object of incorrect type. For example, TypeError is raised every time you try to concatenate an integer with a string.

In this article, we will dig deep into the “TypeError: list indices must be integers or slices not tuple” error and how beginners can debug and fix it quickly and effectively.

“TypeError: list indices must be integers or slices not tuple” indicates that you’re accessing a Python list using a tuple instead of an index or an index range. The “list indices” in the error message simply means “list indexes”.

Python beginners often mixed the slice syntax (using colons) with the list syntax (using commas).

Another common thing that cause this type of error is accessing a non-nested list using multi-dimensional slicing.

In order to fix the error, make sure you’re using the right syntax with the right object. Let’s see some examples:

# TypeError: list indices must be integers or slices, not tuple
# because of missing comma
a_list = [['a', 'b', 'c']['a1', 'b1', 'c1']] 
Code language: Python (python)

In the example above, we forgot to add a comma when we’re trying to define a nested list, so Python mistakenly recognize it as we’re trying to access a list using indexes, hence display a TypeError.

Find the tuple indexes

There is a chance you may have used a tuple to access a list in a straightforward way, which triggers “TypeError: list indices must be integers or slices not tuple” error. Typically, such source code may look like below (oversimplified example).

a_list = ['a', 'b', 'c', 'd', 'e']
indexes = 0, 1 
result = my_list[my_tuple]
Code language: Python (python)

In real life, the indexes may be the result of another operation, or the result from a function. In Python, typically a tuple is created by wrapping several objects in a parentheses pair (). For example: ('a', 'b') or ('a', 'b', 'c', 'd'). The parentheses are optional, which means 'a', 'b', 'c', 'd' also creates a tuple as well. In addition to that, you can also create a tuple using one of the following ways :

• A pair of parentheses () creates an empty tuple
• 0, or ('a',) also creates a tuple
• Explicitly using tuple() constructor. For example, `tuple(‘a’, ‘b’).

With that many ways to create a tuple, follow the suggestions below to debug your program:

• Use the type class to inspect the type of each object.
• Alternatively, use isinstance to check whether the in object is an instance or a subclass of a class or not.

Check your syntax

In this case, simply inspect and add commas to the list definition accordingly.

# a_list definition with the proper syntax
a_list = [['a', 'b', 'c'],['a1', 'b1', 'c1']] 



  


                       
  



Code language: Python (python)

Another common scenario is using an incorrect index accessor.

a_list = [['a', 'b', 'c'],['a1', 'b1', 'c1']] 
result = a_list[0, 0]
# Will cause TypeError: list indices must be integers or slices, not tuple
Code language: Python (python)

In the example, we two integer separated by a comma to get an element from a nested list. This is the wrong syntax, which causes Python interpreter to mistakenly recognize it as a tuple.

If you’re trying to access an element from a nested list, you would have to use two pair of square brackets to do it. The first bracket pair will return the first element, then the second one will be the index to the element you just got.

a_list = [['a', 'b', 'c'],['a1', 'b1', 'c1']] 
result = a_list[0][0]
# "result" will be 'a'
# This equals to
result1 = a_list[0] # Returns ['a', 'b', 'c']
result2 = result1[0] # Returns 'a'
Code language: Python (python)

In case you want to get a part of the list in Python, use the slicing syntax as follows:

a_list = ['a', 'b', 'c', 'd', 'e', 'f']
print(a_list[0:3]) # returns ['a', 'b', 'c']
print(a_list[:3]) # returns ['a', 'b', 'c']
print(a_list[3:]) # returns ['d', 'e', 'f']
Code language: Python (python)

Here we use the colon to separate the start and end indexes. Both the start and end index are optional. If not specified, the value for start index would be 0 and end index would be defaulted to the length of the list.

How to access multiple, unrelated list items without slicing? Simple, just use an index to access them separately and concatenate them afterwards.

a_list = ['a', 'b', 'c', 'd', 'e', 'f']
print([a_list[0], a_list[2], a_list[4]]) # returns ['a', 'c', 'e']



  


                       
  



Code language: Python (python)

The code doesn’t look very elegant, but it does the job without having to use an external library. Another way to do it is using a for loop like below :

a_list = ['a', 'b', 'c', 'd', 'e', 'f']
indexes = [0,2,4]
result = [a_list[x] for x in indexes]
print(result) # returns ['a', 'c', 'e']
Code language: Python (python)

We hope that the article helped you successfully debug and fix “TypeError: list indices must be integers or slices not tuple” error in Python, as well as avoid encountering it in the future. We’ve also written a few other guides for fixing common Python errors, such as Fix “Max retries exceeded with URL” ,Python Unresolved Import in VSCode or “IndexError: List Index Out of Range” in Python.
If you have any suggestion, please feel free to leave a comment below.

Estimated reading time: 3 minutes

When working with Python lists in your data analytics projects, when you trying to read the data, a common problem occurs if you have a list of lists, and it is not properly formatted.

In this instance, Python will not be able to read one or more lists and as a result, will throw this error.

In order to understand how this problem occurs, we need to understand how to create a list of lists.

How to create a lists of lists

Let’s look at a simple list:

a = [1,2,3]
print(a)
print(type(a))

Result:
[1, 2, 3]
<class 'list'>

Let’s create a second list called b:

b = [4,5,6]
print(b)
print(type(b))

Result:
[4, 5, 6]
<class 'list'>

So if we want to join the lists together into one list ( hence a list of lists) then:

a = [1,2,3]
b = [4,5,6]

list_of_lists = []
list_of_lists.append(a)
list_of_lists.append(b)
print(list_of_lists)
print(type(list_of_lists))

Result:
[[1, 2, 3], [4, 5, 6]]
<class 'list'>

So as can be seen the two lists are contained within a master list called “list_of_lists”.

So why does the error list indices must be integers or slices, not tuple occur?

Reason 1 ( Missing commas between lists)

If you manually type them in and forget the comma between the lists this will cause your problem:

a=[[1,2,3][4,5,6]]
print(a)

Result (Error):
Traceback (most recent call last):
  line 10, in <module>
    a=[[1,2,3][4,5,6]]
TypeError: list indices must be integers or slices, not tuple

But if you put a comma between the two lists then it returns no error:

a=[[1,2,3],[4,5,6]]
print(a)

Result (no error):
[[1, 2, 3], [4, 5, 6]]
Process finished with exit code 0

Reason 2 ( Comma in the wrong place)

Sometimes you have a list, and you only want to bring back some elements of the list, but not others:

In the below, we are trying to bring back the first two elements of the list.

a= [1,2,3,4,5]
print(a[0:,2])

Result:
Traceback (most recent call last):
   line 14, in <module>
    print(a[0:,2])
TypeError: list indices must be integers or slices, not tuple

The reason that the same error happens is the additional comma in a[0:,2], causes the error to appear as Python does not know how to process it.

This is easily fixed by removing the additional comma as follows:

a= [1,2,3,4,5]
print(a[0:2])

Result:
[1, 2]
Process finished with exit code 0

So why is there a mention of tuples in the error output?

The final piece of the jigsaw needs to understand why there is a reference to a tuple in the error output?

If we return to a looking at a list of lists and look at their index values:

a=[[1,2,3],[4,5,6]]
z = [index for index, value in enumerate(a)]
print(z)

Result:
[0, 1]
Process finished with exit code 0

As can be seen, the index values are 0,1, which is correct.

As before removing the comma gives the error we are trying to solve for:

a=[[1,2,3][4,5,6]]
z = [index for index, value in enumerate(a)]
print(z)

Result:
Traceback (most recent call last):
  line 16, in <module>
    a=[[1,2,3][4,5,6]]
TypeError: list indices must be integers or slices, not tuple

BUT the reference to the tuple comes from the fact that when you pass two arguments (say an index value) a Tuple is created, but in this instance, as the comma is missing the tuple is not created and the error is called.

This stems from the __getitem__ for a list built-in class cannot deal with tuple arguments that are not integers ( i.e. 0,1 like we have returned here) , so the error is thrown, it is looking for the two index values to pass into a tuple.