List assignment index out of range python ошибка

In python, lists are mutable as the elements of a list can be modified. But if you try to modify a value whose index is greater than or equal to the length of the list then you will encounter an Indexerror: list assignment index out of range.  

Python Indexerror: list assignment index out of range Example

If ‘fruits’ is a list, fruits=[‘Apple’,’ Banana’,’ Guava’]and you try to modify fruits[5] then you will get an index error since the length of fruits list=3 which is less than index asked to modify for which is 5.

Output:

Traceback (most recent call last):
 File "/example.py", line 3, in <module>
   fruits[5]='Mango'
IndexError: list assignment index out of range

So, as you can see in the above example, we get an error when we try to modify an index that is not present in the list of fruits.

Python Indexerror: list assignment index out of range Solution

Method 1: Using insert() function

The insert(index, element) function takes two arguments, index and element, and adds a new element at the specified index.

Let’s see how you can add Mango to the list of fruits on index 1.

Output:

Original list: ['Apple', 'Banana', 'Guava']
Modified list: ['Apple', 'Mango', 'Banana', 'Guava']

It is necessary to specify the index in the insert(index, element) function, otherwise, you will an error that the insert(index, element) function needed two arguments.

Method 2: Using append()

The append(element) function takes one argument element and adds a new element at the end of the list.

Let’s see how you can add Mango to the end of the list using the append(element) function.

Output:

Original list: ['Apple', 'Banana', 'Guava']
Modified list: ['Apple', 'Banana', 'Guava', 'Mango']

An IndexError is nothing to worry about. It’s an error that is raised when you try to access an index that is outside of the size of a list. How do you solve this issue? Where can it be raised?

In this article, we’re going to answer those questions. We will discuss what IndexErrors are and how you can solve the “list assignment index out of range” error. We’ll walk through an example to help you see exactly what causes this error.

Without further ado, let’s begin!

The Problem: indexerror: list assignment index out of range

When you receive an error message, the first thing you should do is read it. An error message can tell you a lot about the nature of an error.

Our error message is: indexerror: list assignment index out of range.

IndexError tells us that there is a problem with how we are accessing an index. An index is a value inside an iterable object, such as a list or a string.

The message “list assignment index out of range” tells us that we are trying to assign an item to an index that does not exist.

In order to use indexing on a list, you need to initialize the list. If you try to assign an item into a list at an index position that does not exist, this error will be raised.

An Example Scenario

The list assignment error is commonly raised in for and while loops.

We’re going to write a program that adds all the cakes containing the word “Strawberry” into a new array. Let’s start by declaring two variables:

cakes = ["Strawberry Tart", "Chocolate Muffin", "Strawberry Cheesecake"]
strawberry = []

The first variable stores our list of cakes. The second variable is an empty list that will store all of the strawberry cakes. Next, we’re going to write a loop that checks if each value in “cakes” contains the word “Strawberry”.

for c in range(0, len(cakes)):
	if "Strawberry" in cakes[c]:
		strawberry[c] = cakes[c]

print(strawberry)

If a value contains “Strawberry”, it should be added to our new array. Otherwise, nothing will happen. Once our for loop has executed, the “strawberry” array should be printed to the console. Let’s run our code and see what happens:

Traceback (most recent call last):
  File "main.py", line 6, in <module>
	strawberry[c] = cakes[c]
IndexError: list assignment index out of range

As we expected, an error has been raised. Now we get to solve it!

The Solution

Our error message tells us the line of code at which our program fails:

The problem with this code is that we are trying to assign a value inside our “strawberry” list to a position that does not exist.

When we create our strawberry array, it has no values. This means that it has no index numbers. The following values do not exist:

strawberry[0]
strawberry[1]
…

We are trying to assign values to these positions in our for loop. Because these positions contain no values, an error is returned.

We can solve this problem in two ways.

Solution with append()

First, we can add an item to the “strawberry” array using append():

cakes = ["Strawberry Tart", "Chocolate Muffin", "Strawberry Cheesecake"]
strawberry = []

for c in range(0, len(cakes)):
	if "Strawberry" in cakes[c]:
		strawberry.append(cakes[c])

print(strawberry)

The append() method adds an item to an array and creates an index position for that item. Let’s run our code: [‘Strawberry Tart’, ‘Strawberry Cheesecake’].

Our code works!

Solution with Initializing an Array

Alternatively, we can initialize our array with some values when we declare it. This will create the index positions at which we can store values inside our “strawberry” array.

To initialize an array, you can use this code:

This will create an array with 10 empty values. Our code now looks like this:

cakes = ["Strawberry Tart", "Chocolate Muffin", "Strawberry Cheesecake"]
strawberry = [] * 10

for c in range(0, len(cakes)):
	if "Strawberry" in cakes[c]:
		strawberry.append(cakes[c])

print(strawberry)

Let’s try to run our code:

['Strawberry Tart', 'Strawberry Cheesecake']

Our code successfully returns an array with all the strawberry cakes.

This method is best to use when you know exactly how many values you’re going to store in an array.

Our above code is somewhat inefficient because we have initialized “strawberry” with 10 empty values. There are only a total of three cakes in our “cakes” array that could possibly contain “Strawberry”. In most cases, using the append() method is both more elegant and more efficient.

Conclusion

IndexErrors are raised when you try to use an item at an index value that does not exist. The “indexerror: list assignment index out of range” is raised when you try to assign an item to an index position that does not exist.

To solve this error, you can use append() to add an item to a list. You can also initialize a list before you start inserting values to avoid this error.

Now you’re ready to start solving the list assignment error like a professional Python developer!

IndexError: list assignment index out of range

List elements can be modified and assigned new value by accessing the index of that element. But if you try to assign a value to a list index that is out of the list’s range, there will be an error. You will encounter an IndexError list assignment index out of range. Suppose the list has 4 elements and you are trying to assign a value into the 6th position, this error will be raised.

Example:

list1=[]
for i in range(1,10):
    list1[i]=i
print(list1)

Output: 

IndexError: list assignment index out of range

In the above example we have initialized a “list1“ which is an empty list and we are trying to assign a value at list1[1] which is not present, this is the reason python compiler is throwing “IndexError: list assignment index out of range”.

We can solve this error by using the following methods.

Using append()

We can use append() function to assign a value to “list1“, append() will generate a new element automatically which will add at the end of the list.

Correct Code:

list1=[]
for i in range(1,10):
    list1.append(i)
print(list1)

Output:

[1, 2, 3, 4, 5, 6, 7, 8, 9]

In the above example we can see that “list1” is empty and instead of assigning a value to list, we append the list with new value using append() function.

Using insert() 

By using insert() function we can insert a new element directly at i’th position to the list.

Example:

list1=[]
for i in range(1,10):
    list1.insert(i,i)
print(list1)

Output:

[1, 2, 3, 4, 5, 6, 7, 8, 9]

In the above example we can see that “list1” is an empty list and instead of assigning a value to list, we have inserted a new value to the list using insert() function.

Example with While loop

num = []
i = 1
while(i <= 10):
num[i] = I
i=i+1
 
print(num)

Output:

IndexError: list assignment index out of range

Correct example:

num = []
i = 1
while(i <= 10):
    num.append(i)
    i=i+1
 
print(num)

Output:

[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

Conclusion:

Always check the indices before assigning values into them. To assign values at the end of the list, use the append() method. To add an element at a specific position, use the insert() method.

1. Python IndexError: list assignment index out of range
2. Fix the IndexError: list assignment index out of range in Python
3. Fix IndexError: list assignment index out of range Using append() Function
4. Fix IndexError: list assignment index out of range Using insert() Function
5. Conclusion

In Python, the IndexError: list assignment index out of range is raised when you try to access an index of a list that doesn’t even exist. An index is the location of values inside an iterable such as a string, list, or array.

In this article, we’ll learn how to fix the Index Error list assignment index out-of-range error in Python.

Python IndexError: list assignment index out of range

Let’s see an example of the error to understand and solve it.

Code Example:

# error program --> IndexError: list assignment index out of range
i = [7,9,8,3,7,0]  # index range (0-5)
j = [1,2,3]        # index range (0-3)

print(i,"n",j)
print(f"nLength of i = {len(i)}nLength of j = {len(j)}" )

print(f"nValue at index {1} of list i and j are {i[1]} and {j[1]}")
print(f"nValue at index {3} of list i and j are {i[3]} and {j[3]}") # error because index 3 isn't available in list j

Output:

[7, 9, 8, 3, 7, 0]
[1, 2, 3]

Length of i = 6
Length of j = 3

Value at index 1 of list i and j are 9 and 2

IndexError: list assignment index out of range

The reason behind the IndexError: list assignment index out of range in the above code is that we’re trying to access the value at the index 3, which is not available in list j.

Fix the IndexError: list assignment index out of range in Python

To fix this error, we need to adjust the indexing of iterables in this case list. Let’s say we have two lists, and you want to replace list a with list b.

Code Example:

a = [1,2,3,4,5,6]
b = []
k = 0

for l in a:
    b[k] = l # indexError --> because the length of b is 0
    k += 1

print(f"{a}n{a}")

Output:

IndexError: list assignment index out of range

You cannot assign values to list b because the length of it is 0, and you are trying to add values at kth index b[k] = I, so it is raising the Index Error. You can fix it using the append() and insert().

Fix IndexError: list assignment index out of range Using append() Function

The append() function adds items (values, strings, objects, etc.) at the end of the list. It is helpful because you don’t have to manage the index headache.

Code Example:

a = [1,2,3,4,5,6]
b = []
k = 0

for l in a:
   # use append to add values at the end of the list
    j.append(l)
    k += 1

print(f"List a: {a}nList b: {a}")

Output:

List a: [1, 2, 3, 4, 5, 6]
List b: [1, 2, 3, 4, 5, 6]

Fix IndexError: list assignment index out of range Using insert() Function

The insert() function can directly insert values to the k'th position in the list. It takes two arguments, insert(index, value).

Code Example:

a = [1, 2, 3, 5, 8, 13]
b = []
k = 0

for l in a:
    # use insert to replace list a into b
    j.insert(k, l)
    k += 1

print(f"List a: {a}nList b: {a}")

Output:

List a: [1, 2, 3, 4, 5, 6]
List b: [1, 2, 3, 4, 5, 6]

In addition to the above two solutions, if you want to treat Python lists like normal arrays in other languages, you can pre-defined your list size with None values.

Code Example:

a = [1,2,3,4,5,6]
b = [None] * len(i)

print(f'Length of a: {len(a)}')
print(f'Length of b: {len(b)}')

print(f"n{a}n{b}")

Output:

Length of a: 6
Length of b: 6

[1, 2, 3, 4, 5, 6]
[None, None, None, None, None, None]

Once you have defined your list with dummy values None, you can use it accordingly.

Conclusion

There could be a few more manual techniques and logic to handle the IndexError: list assignment index out of range in Python. This article overviews the two common list functions that help us handle the Index Error in Python while replacing two lists.

We have also discussed an alternative solution to pre-defined the list and treat it as an array similar to the arrays of other programming languages.

[SOLVED] List Index Out of Range Meaning, How to Fix | Python Program.

If you are frequent in Python programming, you will definitely come across this error message, “indexerror: list index out of range“. You might want to ask, what does list index out of range mean? and how to fix the list index out of range in python?

Well, in this article, I will share with you everything you need to know about this common list assignment index out of range error in Python. Here, you will follow this guide and fic the error once and for all. After reading this post, you will find yourself at a position where you can even teach others on how to fix this error message.

Why do you have “List Index Out of Range” Error?

If you write a simple python program, as follow;

l=[1,2,3,0,0,1]
for i in range(0,len(l)):
       if l[i]==0:
           l.pop(i)

This will give you an error message ‘list index out of range’ on line if l[i]==0:

And you will observe that i is getting incremented and the list is getting reduced.
However, you may have a loop termination condition i < len(l).

See other explanations here:

check out the following code in python

1. >>> even = [ 2, 4, 6, 8 ]
2. >>> even[1]
3. 4
4. >>> even[3]
5. 8
6. >>> even[5]
7. Traceback (most recent call last):
8. File “<pyshell#7>”, line 1, in <module>
9. even[5]
10. IndexError: list index out of range

So in the above code, we have defined an even list that contains 4 elements with starting index 0 and last index 3.

clearly, this means you can’t access any elements in even list if you go beyond your last index value.

And if u try, then u will get a list index out of range error.

List index out of range means that you are providing an index for which a list element does not exist. Index out of range means that the code is trying to access a matrix or vector outside of its bounds.

In python list is mutable, so the size is not fixed.

Due to size is not fixed, the available index is greater than the assigned index for a list(available index > assigned index).

2 Ways to Fix List Index Out of Range Error

l = [x for x in l if x != 0]

i = 0
while i < len(l):
   if l[i] == 0:
       l.pop(i)
   else:
       i += 1

If you try to access the empty or None element by pointing available index of list, Then you will get the List index out of range error.

open python and dirty your hands with this below code, to have a better understanding.

>> x = list(‘1234’)

>> x

[‘1’ , ‘2’ , ‘3’, ‘4’]

>> length = len(x)

4

>> x[length]

Index Error: list index out of range

Final Answer [SOLVED]: If you have a list with 53 items, the last one is thelist[52] because indexing starts at 0 (zero).

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