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Filtering II: For Loop Example

Using List Comprehensions Effectively Dan Bader 00:49

This lesson continued the discussion on filtering, this time using a for loop to generate a list of squares. The for loop does exactly what the list comprehension from the last lesson did and the output is the same.

You saw that, using a for loop, the code turns out this way:

>>> even_squares = []
>>> for x in range(10):
...     if x % 2 == 0:
...         even_squares.append(x * x)

00:00 So, if you wanted to generate the same list with a for loop, you would probably do something like this. Again, you would start out by creating an empty output list, and then we would iterate over this range again.

00:13 And now what we need to add is the filtering. So in this case, I would just add the filtering condition here, inside the for loop,

00:24 and then if the filter condition is True, only then am I going to append the calculated value to my output list. This is exactly what I’ve done here, so hopefully, we’ll get the same result. Yup—that looks pretty good.

00:39 You can see here how I took the initial list comprehension with filtering and transformed it into an equivalent for loop.

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