Welcome back.
Let's keep going with some more string methods.
Now we've learned about adding and removing ones.
We learned about append, insert and extend.
And then in removing, we learned about pop, remove and clear.
There's a few other important ones.
Let's go with the index.
So instead of clearing here, let's clean this up.
And we'll do basket dot.
Index.
An index.
As you can see, we give it a value, a start and a stop.
What does that mean?
Well, we want to say, hey, what index is number two?
If we do index of two and I click run.
It's going to give me one.
I know this is a little confusing, but it's asking for the index.
Where is number two?
Number two is at index of one.
Let's change these into letters just so it's more clear.
So we have a B.
See.
D.
And then finally, E.
And again, if I do.
D here and I click Run.
I get an index of three because zero one, two, three, it's on shelf three in our memory.
And you can also do a optional parameter here, which is where should we start looking?
So I want you to start looking at index of zero and then finish looking at index of two.
If I do run here, I get an error.
It says, hey de is not in list because well, we started at index of zero and stopped an index of two.
If I do three and I click Run.
No, it stops right before three.
So if I do four.
And I click Run.
There you go.
I get three.
Now.
Errors are not good in our programs.
Ideally, we don't want to get errors, so how can we avoid this?
What if we're looking for something and we're not sure if it's in the list or not?
There's another nifty way of looking for things in a list, and this involves what we call a python
key word.
A key word is something that you use in Python that well already has some meaning.
For example, a key word here if I go to Python.
Key words are all these words that already mean something.
Now we're going to go through them, and we haven't seen a lot of them yet, but we might have seen
true right in boolean values to mean something.
So in Python we can't really use the word true because well, it already means something.
There's a word called in that, as you can see, as soon as we type mean something is a key word in
python and this is quite nice we can say hey is DX in basket and if I run this.
I get true OC is ex and basket.
I get false because, well, it doesn't exist.
And this is actually quite useful.
And we can even do it for strings.
For example, if I'm looking for, let's say, the letter I in a word and let's say it's I in.
Hi, my name is Ian.
If I click Run.
I get true because the letter I.
Does exist in this string.
All right, let's learn another one.
Another one is basket dot count.
And we can count how many times an item occurs.
So, for example, if I do, DH and I click Run.
I get one because DD only exists once in the list.
But if I add another DH in here and I click run.
We get to.
It counts how many times this value occurs in our list?
Very, very useful.
All right.
A few more still to go.
Let's do some exercises and I'll see you in the next one.