‫Welcome back.
‫Let's talk about some useful tricks with lists that you'll see a lot in Python code.
‫Well, one we have already seen, it's this idea of length.
‫You're going to be using this a lot.
‫That is to figure out the length of a list.
‫Which in our case is now seven.
‫Another really useful trick is to reverse a list.
‫Now, I've already showed you how to reverse a list, but sometimes you can do that with list slicing
‫again, something that we've seen in string slicing, so I can actually do basket.
‫And then semicolon semicolon negative one.
‫If I click run here.
‫Is that what you expected?
‫Let's go through this line by line.
‫I've sorted the basket so that it's from a all the way to Z, and then I've reversed this.
‫So it's in Z all the way to A and then I've reversed the basket again so that instead of being in reverse,
‫it's now in order.
‫A.
‫B.
‫C.
‫D.
‫E.
‫X.
‫And this list slicing creates a new list.
‫Right.
‫If I print basket here.
‫You'll see that the basket is the reversed version, the last action that we've taken on it versus list
‫slicing that creates a new version.
‫So this notation, you'll see a lot with lists when you need to reverse a list, or maybe you need to
‫make a copy of the list like this.
‫Or maybe you need a portion of the list.
‫Another useful thing that you'll see a lot of is something called range.
‫Let's comment this out for now.
‫If I wanted to generate a list really quickly, let's say from 1 to 100, I can do something like this.
‫I can say range and then start and then stop.
‫So let's do 100.
‫And if I print this.
‫And I run.
‫I get a range 1 to 100.
‫But if I wrap this in a list.
‫Which is going to create a new list for us.
‫And I click Run.
‫Look at that.
‫I get a range from one all the way to 99.
‫Remember, it's the start and then whatever to stop it.
‫So before it hits 100, it's going to stop.
‫Now, if I remove this and just do one single thing.
‫I get a list starting from zero all the way to 99 if I want a list that has 101 items because it starts
‫at zero.
‫I would just do 101.
‫And range is something we'll talk about a lot more, especially when we talk about loops in programming.
‫But this is a great way of you to generate a list really, really quickly, especially a numbered list.
‫Finally, the last common thing that you'll see a lot is this idea of dot joint join.
‫What is dot joint join is actually something that works on strings.
‫It's a string method, but it's often used this way.
‫We have an empty string.
‫And this empty string, let's say, sentence.
‫And then we can do sentence.
‫Dot join.
‫And join takes what we call an iterable, which is a list for now.
‫And in here, we can have a sentence like, hi.
‫My name.
‫Is.
‫Jojo.
‫And now if I print sentence.
‫And I click run here.
‫Hmm.
‫I don't get anything.
‫Let's figure out why.
‫What if I type in an exclamation mark here and I click run?
‫All right.
‫It's printing out sentence, but it looks like Dot Join creates a new item for us, so let's just assign
‫that to new sentence.
‫Now if I do new sentence and print that out.
‫We see that again.
‫Hi, my name is Jojo.
‫Hmm.
‫So this is a little funky.
‫Right.
‫We have these exclamation marks.
‫Between our items and join joins these little iterable items these lists by whatever is in front of
‫it.
‫So if we actually change this to an empty string click run, we now get this if I add a space in between
‫and click Run.
‫We get?
‫Hi, my name is Jojo.
‫And sometimes you'll notice this pattern a lot, especially if you want to join and create a new string
‫out of a list of items.
‫Now, a shorthand way of doing this is to actually not even bother with this and just doing an empty
‫string.
‫Dot join and then joining all the list items.
‫There we go.
‫So all we're doing is combining lists into a string.
‫And this is a common pattern that you'll see a lot of I'll see in the next one.
‫Bye bye.