Zip - Intermediate Python Programming p.8

Key Takeaways

what is going on everybody Welcome to part eight of our intermediate Python Programming tutorial Series in this tutorial what we're going to be talking about is zip the zip function takes elements from multiple iterables and Aggregates them into one where we basically share the index value let's say so I think it's easier to understand if we just show it really quickly so we're going to work with the following data as soon as I found my mouse say x is equal to 1 2 2 three and four uh I can't remember I think I've covered it already but in according to Pepe when you make a list like this it's comma space just no spaces in the parameters of a function for example um but it's really tempting for me personally to do things like uh this instead so sorry if I do that but in theory pep eight should be like this so we're just going to have some simple uh some simple lists you don't have to make them exactly as I do just just have some lists I'm just here showing that we can bring together lists of different types or data from lists of different types okay so first let's go ahead and combine uh X and Y so what we can say is for a b in zip XY print a so the intuition here what's supposed to happen is it's going to tie together X and Y so we should see 1 7 2 six 32 and 41 let's see what we get sure enough 1726 3241 as expected so we can also do multiple elements so we can say a b c and zip XY Z and of course we get the exact same thing now what if we just said uh what if instead we just said we wanted to to cuz in here we're basically iterating over the result of zip XYZ so you might be thinking okay zip XYZ must equal a list of either tupes or lists of uh these pairs or triplets I suppose anyway um you might think that that's what's happening but it's not so let's go ahead and look at what is print zip XY Z it is a zip object now a zip zip object can be iterated over so of course we can say for I in zip XYZ print I and we see um it is tupes of the values okay so that makes sense another thing that we could do say you didn't want to just iterate over them we actually can convert a zip to a list so actually I'll just convert this one up here you can just say I want this now to be a list of the zip and we can print that out and that works as well also interestingly uh it won't work with three values but with two values you can say rather than list we can convert it to a dict and now you have dictionary where the key is that first Val value and the uh value is a second value so we can also obviously combine zip with list comprehension so we can do things like print ABC for ABC in zip XYZ not too not too surprising nothing to write home about here um but I do want to point out a potential issue that if you're commonly using this code and then you might revert back to a for Loop and you're comparing the two and you're like what is happening because the for Loop is doing something different I'll show you what can happen so sometimes it might be tempting to take this line and instead maybe we're going to we could write this we could print print XY and we'll just do XY 4xy IN Zip XY uh um seems Seems good right so we'll run that and we get what we expected and then later on if we decided we wanted to print x uh is X what we expected X to be 1 2 3 4 yep that is what we thought X was going to be because we know that these are um temp temporary variables right in a for Loop but H is that the case so what if we said 4 a b or print AB for ab IN Zip XY and then we print a after that so this these variables okay we get a is not defined but what if we did the same list comprehension just in a typical for Loop well we would say for a IN Zip X Y print a a same thing I'm just going to comment this out but it's the same it's going to produce the same output anyway but see what happens on the print a huh looks like that a was stored what's more is instead of before when we when we said in the list comprehension example for XY or print xy4 XY IN Zip XY we recognized that these were just temporary values they weren't actually being stored but in the for Loop they are stored So when you say print uh or for XY and zip XY this will work it's going to work it's going to be fine no one's going to lose their shirt but when we go to print X afterwards let me just comment this out um it's it's overwritten XY so you might find yourself in a scenario where you're not using list comprehension you're writing a simple for Loop and because you've gotten away with this in list comprehension you think you're going to get away with it here but you don't and then you decide that you're going to iterate again like for x or for I INX or something like this you're going to continue using that X variable and it's just not going to work so just remember that in list comprehension these values aren't going to overwrite your original variables and in fact they're not even stored after the loop but uh or after the full iteration is complete but in a regular for Loop that value is stored and it's going to overwrite your old old variables so if you get in the habit of just using the same variable names as you're iterating over it it's probably a bad idea because you're going to you might find yourself in a situation like this so anyways that's zip if you have any questions comments concerns or whatever feel free to leave them below otherwise I will see you in the next tutorial