‫Let's talk about set comprehension and dictionary comprehension.
‫Now this first one is actually quite easy, you see, because we can do the same thing that we've done
‫with lists.
‫We simply change these bracket notation to a set, which is a curly bracket like this, so that if I
‫do my list.
‫The first one, I get a set.
‫Same with the second one.
‫If I go like this.
‫My list to.
‫Just like that.
‫And I think you get the idea.
‫Let's do one more on the final one.
‫So my list for.
‫Again, you're able to do a set comprehension on sets as well.
‫A quick way for us to generate sets.
‫I remember sets only allow numbers that are not duplicate only unique items.
‫What about dictionary comprehension?
‫Well, let's do something like this.
‫Using the same formula we've used.
‫Let's create a my debt.
‫And in here, we're going to create a key and a value just like that.
‫And this key value.
‫Can be acted upon.
‫So in our case, let's say we want to multiply the value by two or to the power of two.
‫So this is what we want to create a key value pair and the value gets acted upon.
‫Now in here, I'm going to say another for loop for.
‫So let's say key value.
‫And then in.
‫Well.
‫And what?
‫What are we going to iterate over?
‫Well, let's think here.
‫In order for us to create a dictionary, we need both a key and a value.
‫Right.
‫So I need to pass it an iterable, but I need to pass it an iterable like a dictionary that has both
‫key and value.
‫So we can do something simple here.
‫We can say simple dictionary that will have.
‫A as one.
‫And be.
‫As to.
‫And now all we do is pass simple dictionaries in here.
‫As an iterable.
‫We grab the key and values by doing dot items, which we've seen before.
‫And let's make this a little bit bigger.
‫There you go.
‫Let's put it all the way.
‫Just so we're all clear.
‫It's all on one line.
‫And now let's just see what happens and we'll go through it step by step.
‫I'm going to copy this and paste it.
‫And if I click Run.
‫Look at that.
‫I have a new dictionary that has a equal to one and be equal to four.
‫Now, let's go through it one by one.
‫Just like we saw with list and set.
‫The first part is what we want to do with the data.
‫In our case, I wanted key and value, which I was going to extract here in our for loop.
‫I could have named this whatever I want though I could have done K and V and you might see this commonly
‫in python code just short term for key and value.
‫And then I wanted to do the power of two to the value.
‫So then this is what I wanted to do.
‫This is the action.
‫This is the four loop that we did.
‫So the for loop was, hey, extract the key and value using the dictionary dot items.
‫Remember I needed to have two values so I can fill in key and value.
‫And then the value you multiply by two or to the power of two.
‫So we get that.
‫If for example, I wanted to add an if statement and say, Hey, I only want you to add.
‫If the value.
‫Is even.
‫So let's say modulo two equals zero.
‫Only then I want you to add the dictionary if I click Run.
‫Only the even value for gets added to the dictionary.
‫Very, very cool.
‫Again, this makes your code a little bit less readable, so it's just a shorthand for you to use.
‫And maybe if you see it in code, you at least know what it is.
‫But you should be careful not to be overly clever and do the single line dictionary comprehension just
‫because you can.
‫Just to solidify our knowledge.
‫Let's finish up with another example.
‫What if instead I have this.
‫I want to do a four.
‫Number in a list.
‫One, two, three.
‫So we no longer have this dictionary, but we still need to include a key and a value pair.
‫Could I do it so that maybe the item is the key and the item multiplied by two is the value?
‫How would we do that?
‫Pause the video and give it a go if you want otherwise.
‫This is how we do it.
‫We simply say number is the key and the value will be num times two.
‫Just like that.
‫Nothing too difficult.
‫Right?
‫If I click run.
‫There we go.
‫We're able to use comprehension.
‫List comprehension set comprehension dictionary comprehension as a way to create lists with Python,
‫as a way to create these data structures really fast with Python.
‫Let's take a break and do an exercise in the next video.