Why Does List Assignment Fail with IndexError in Python, and How Can I Append Elements Correctly?

Why List Assignment Fails with IndexError: Appending Elements Correctly

When attempting to create a list by assigning each element individually, you may encounter an IndexError. This issue arises when you designate indices in an empty list that don't exist yet.

For instance, consider the following code:

i = [1, 2, 3, 5, 8, 13]
j = []
k = 0

for l in i:
    j[k] = l
    k += 1

When you run this code, you'll get an "IndexError: list assignment index out of range" error. To resolve this issue, you should use the append() method to add elements to the end of the list:

for l in i:
    j.append(l)

However, if you desire an array-like behavior, you can pre-populate your list with None values and then overwrite them at specific indices:

i = [1, 2, 3, 5, 8, 13]
j = [None] * len(i)
k = 0

for l in i:
    j[k] = l
    k += 1

In conclusion, Python lists require pre-existing indices for assignment and offer the append() method for easy extension. To emulate an array, you can manually create a list with None placeholders and then assign values by index.

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