Trying to understand why this is the output

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I am currently learning python and working my way through a course, just done an end of module exam. There was one question I got wrong but I don't understand how the output is what it is.

Python

my_list = [3, 1, -2]
print(my_list[my_list[-1]])

The output is 1, can some explain why that is please?

What I have tried:

I have searched around the internet with not luck

Posted 29-Jul-21 10:49am

Luke 2

Updated 29-Jul-21 11:19am

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OriginalGriff · Accepted Answer · 2021-07-29T11:19:00

Solution 1

Python allows negative indexes to lists, with -1 being the last item, -2 the second to last, and so forth.
So your code:

my_list = [3, 1, -2]
print(my_list[my_list[-1]])

Is the equivelant of:

index = my_list[-1]
print(my_list[index])

Since -1 is the last element of the list, index becomes -2, which accesses the second to last element of the list and prints it: 1

Posted 29-Jul-21 11:19am

OriginalGriff

Comments

Luke 2 29-Jul-21 17:30pm

Thank you. That helps me understand it completely.

OriginalGriff 29-Jul-21 17:32pm

You're welcome!