Python Foundations - Assessments

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Lists v/s Strings

For traversing the list, it's just like the strings,

a = [1,2,3,4,5]
for number in a:

This prints the elements within the list. But, if we want to write or update the elements, we need to deal with the indices. A common way to do that is to combine the functions range and len:

for number in range(len(a)):
    a[number] = a[number] + 1

Since lists are mutable, it increases every number by 1 within the list. Here, len returns the number of elements in the list and range returns a list of indices from 0 to n-1, where n is the length of the list.

The + operation that concatenates two strings also works with lists,

a = [1,2]
b = [3,4]
c = a + b

It prints the concatenated list as [1, 2, 3, 4].

For a list, we can use * to repeat it a given number of times,

a = [1,2,3]    
c = a * 3

Can you guess the output? Enter the sum of all elements of in c

We can also slice the list just like strings,

a = [1,2,3,4,5,6,7,8,9]
s = (a[2:5])

Enter the sum of all elements of in s

A slice operator on the left side of an assignment can update multiple elements:

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

Now, can you tell the sum of all elements inside a

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