Iterating Through Lists

Description

Due to the nature of an index of a list, we can use a for loop to easily iterate through its contents. Remember that we call a specific list item using the name of the list and the index in brackets, like so: A[1].

Sage Cell

Code

A = [ 2, 3, 5, 7, 11 ]
for i in range (0, len(A)):
    print A[i]

Options

Iterating Backwards

Using negative indices, we can iterate through a list backwards. Note that negative indices start at -1, not , and for loops themselves can not iterate backwards, so we start the range at 1 and end it at the length of the list, inclusively. This requires us to set the range for list A as (1, len(A) + 1), as the second value in the range is exclusive.

Code

A = [ 2, 3, 5, 7, 11 ]
for i in range (1, len(A) + 1):
    print A[-i]

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Date: 25 Mar 2019 12:03

Submitted by: Zane Corbiere

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