So I'm going to start with this list of users which if you remember back to our first guide on lists this is representing what you'd get back in some type of database query. And so I'm going to start off just so you can watch the way that the list develops. And so we're going to print out all of our users just like we have right here it looks like everything is working properly.

And now let's look at the first way that we can remove an item and thankfully it has a very nice easy to remember name. We are going to say users and then we're going to call the function remove and remove takes an argument and it takes the value that we're trying to remove. So if I want to remove myself, I can say users which is the list dot remove. So we're calling this function on the list and we're passing in the element that we want to remove. So if I. And let me also print this out. So you can see the difference. So now I can run this and you can see the updated list does not have me in there. Just as Kristine Tiffany and Leanne I used to be at the index of two and I have been removed.

Now, this is a very nice and handy way of being able to extract users or elements from an array like this because usually in many other languages you would have to run a query if you only had the value find the index and then remove that index manually. But with the remove function available in Python we can do this all in a single step so that is very helpful. So that's one way that you can remove elements from a list. Now let's look at another one and this is a very common one I want you to become familiar with this and this is the process of popping. And so I'm going to create a new variable called popped_user and I'm going to show you why I'm doing this in a second. And in order to do this, I say users.pop and pop doesn't take any argument. So we're simply going to say users.pop and what this is going to do is it's going to look at our users list here. And this is the updated one so we have three elements three string elements inside of it and what pop is going to do is it's going to remove the very last element. So, in this case, that is going to be this string of Lee Ann but pop doesn't simply delete an item pop actually returns that item so that you can use it.

And this is the reason why pop is used so much and it's not just in Python. If you're learning other languages pretty much every language I've ever worked with has a form of pop and usually, it's actually called pop because it's a nice visual way of remembering it if you think of this list as a stack of items. You are popping the last item of the list off and when you do that you actually are grabbing it which means you have access to it. So the process is going to occur here is going to be we have this users list when we call the function pop on it. It's going to go find the last element and then it's going to return that. And because I'm saying popped_user = users.pop() it's actually going to store that user inside of this variable. So it is removing the element but it's giving it to us in a way that we can use it. So let's see what this looks like so I'm going to say print and popped user just like this. And then let's also see what the users list looks like now. So if I run this you can see that we get our last element this string of Leann and if we look at what the users list looks like now it only has two elements so we started with four we removed one then we popped one but we were able to use that element and then now we're left with two.

Now if you want. If this concept is still seemingly kind of pointless let me give you an example imagine a scenario where you're wanting to go through this full database list and you're wanting to process it such as sending a payment notification or something like that to the users as you're going through that database query which you have a list as you go through each one.

You can go through and loop over pop the last one on the list off work with it such as sending a notification and then you don't have to worry about sending that user a duplicate because you're able to continually loop through the list will shrink as you're going through it. And each time because you're popping it you're able to work with that one user. And so that's one use case there are, as you're going to see in your python development journey, many different times and algorithms that pop comes in incredibly handy. So we've gone through two different ways to remove elements from a list.

Now let's look at one other one and this is just a pure delete. And so with that we're going to call del. So just DEL which is short for delete and this is where we can pass in an index value. So del is going to take one argument here which is users which is the list and then you have to pass in whatever the index is. And so if I copy this and run it. If you notice the user at index 0 is Kristine. So this should delete Kristine from the user database. We should only have a single element in the list of Tiffany. So if I run this you can see that's exactly what we have.

And so let's kind of take a review on each one of these because there's a reason why there are three ways to remove items from a list in Python. They all have a very specific use case.

If you are working with a list where you know the value, then this remove function and passing in that value is typically the way to go. This makes it possible to simply search through the entire collection and then remove any element that matches this value.

Now moving down the next option pop this is what you're typically going to use when you want the very last element in the list and you want to use that you want to pop it off the stack and use it in your program.

Last on the list is this del command. And this is what you would use when you know the list. And you know the index value for the list. And so that is one of the very common ways to do it. Whenever the only element that you have is the index and you simply know that you want to remove an item at position 0 and that is going to be a very good option to use whenever the index is what you're working with.

Code

users = ['Kristine', 'Tiffany', 'Jordan', 'Leann']

print(users)

users.remove('Jordan')

print(users)

popped_user = users.pop()

print(popped_user)
print(users)

del users[0]

print(users)