#100DaysOfCode in Python Transcripts
Chapter: Days 16-18: List comprehensions and generators
Lecture: Use generators to build a sequence
0:00 A common use case I find for generators
0:02 is to build up my sequence.
0:04 So, let's define a list of options.
0:07 Red, yellow, blue, white, black, green, purple.
0:12 And in my older code, I will do something like,
0:22 And that's fine, we just keep an internal list,
0:26 and append to it and return it.
0:30 Just to show you how you can do this in a more
0:32 concise way with a generator.
0:35 I'm just calling it the same name,
0:38 but appending _gen.
0:40 It's the same for loop,
0:42 but instead of building up a new list,
0:44 I'm going to use the yield keyword
0:46 to yield the values one by one.
0:52 Alright, let's see what that gives us, a generator.
0:59 And a way to materialize the generator
1:03 at one go is to convert it into a list,
1:12 and there you go. So this is a shorter, more concise way
1:14 to build up a list or sequence,
1:16 and it's also faster if your data set grows,
1:20 because it's evaluated lazily.
1:23 And actually to show that in practice,
1:24 in the next section, I will compare a list
1:27 and a generator in performance.