List Comprehension - Python Quick Tips

Key Takeaways

hello everyone and welcome back so in this video I'm going to be talking about list comprehension that most people are aware of what list comprehension are but they don't actually know the proper ways to use it or some of the other methods that can go with it so so I'm gonna be showing here so what means list comprehension is a faster way to build a list not computationally but just in terms of writing blinds so for example if I'd like to build a list X here and let's say I want it to have the value 0 to 10 well rather than creating a for loop and saying for I in range 10 and then appending values in there from the for loop I can do that directly inside of my list right here so I can do something like I for I in range 10 and if I run this now you see we get a list that goes from 0 to 10 so essentially you put here on the left side what you want to be populated in the list then you do the condition here which is for I in range 10 and that will run change I ten times and populate the list now most people know this but it gets way more advanced than this and you can even add conditions afterwards so you can do something like for I in range if I modulus two equals equals zero which means you're only gonna get even numbers in your list here so now we get 0 2 4 6 8 and so on now we can do more conditions and we can add even more things so I can do something like I comma Y for I and range 10 for Y in range 20 now this is gonna look a little bit ridiculous but you guys get the point here what this will do now is build us every single combination of these two for loops so essentially every time this loop runs this loop will run which means we're gonna get 0 0 1 0 2 0 3 0 4 0 5 and so on and then 1 1 1 1 1 and all of that so it's a fast way to build lists and you can do some cool things with it now let's say we don't want to do something necessarily like that what we can do is also put a list inside of a list so I can do a list for I and range 10 if I print this now we get a bunch of lists inside of this list and then inside here I could put another before loop so for I in range 5 and maybe I don't want to have I maybe I don't want it to go counting up from 1 2 3 4 5 well I can just put 0 for I in range five and if I do this then I get a list full of zeros in the same sense I could do something like true for I in range five and then I get a list completely full of troops then I can put another if statement inside of here and you get the point it can go on infinitely now I can even do another list here and keep building and keep building and keep building and that is kind of how this comprehension works so this is very useful it can save you a lot of time and especially when you're creating multi-dimensional lists you just need to set up rows and columns it's very fast to just do something like this where you have you know 0 for I and range 5 for I in range let's say 5 and that will make you you know a 5 by 5 grid of arrays here that you guys can use in access so anyways that has been list comprehension there is some more to this but this is the basics and what most of you will end up using an everyday programming if you guys enjoyed make sure you leave a like and again let me know what you want to see in more Python quick tips