Loops & Conditionals

Loops

Loops perform some operation on a value in a set of values. Let's go through an example using our coverage list from the previous note:

for i in coverage:
    print(i)

Here we see that i is a substitute for some value in the sequence provided - in this case 200, 34, 300, 98, 789, 542.

Nested Loops

Loops can also nested where a loop is placed inside a loop:

for i in [1,2]:
    for j in coverage:
        print(j*2)

Here we move through the loop and for every value in the first list ([1,2]), Then for each pass of the first loop we move through values the second list ([200, 34, 300, 98, 789, 542]). Finally for each value i we then multiply by each value j.

Pass Statement

If you want a placeholder for your loop, meaning no operation is performed, use the pass statement:

for i in coverage:
    pass

Conditionals

If we were interested in performing some operation on a value only if a condition is met, we can use an if statement:

for i in coverage:
    if i > 500:
        print(i)
    else:
        pass

789
542

Here we use the comparison operators we mentioned in the Libraries & Data Frames Topic Note to only print values in coverage if they are larger than 500.

Multiple Conditionals

To perform operations based on multiple conditions you can add in elif statements:

for i in coverage:
    if i > 500:
        print(i)
    elif i < 500:
        print('This value is less than 500')

This value is less than 500
This value is less than 500
This value is less than 500
This value is less than 500
789
542