23. Sets and Frozen Sets [Python 3 Programming Tutorials]

Key Takeaways

today we have another fun topic called sets and frozen sets let's begin with the formal definition of set a set is an unordered collection of unique elements so this is something that you already learnt in your mathematics class while you were in school this is exactly the same thing so I'm going to initialize my first set so let's say I have a basket of fruits and I want to represent that using the set in Python so this is how I do it you should use curly brackets right and then you should add all your elements in this set so I have a bunch of fruits that I have placed in my basket I love mango by the way it's summer and in India the lot of mangoes coming out and they taste so good and then I have some repeated elements I had to april's in my basket two oranges and one mango so I just created a set when I do type of basket it is telling me that the type is sad now let's print the content of basket when I do that you notice that orange was praising two times in my basket but this one is just showing one time so that's what unique element aspect means a set doesn't allow duplicate elements so it will remove duplicates automatically so set could be useful when you want to have on the unique elements for doing anything okay there is another way to initialize set which is by doing this so I can just in his last act like this and then you can add the elements into it so for example I am going to add whatever number be doc so I a dot okay when I print a I get one and two all right now when you initialize the set using the first index which is curly brackets remember that you don't use empty curly brackets because when you do that it is gonna initialize it as dictionary you see this and if I have a is equal to something if I have as long as I have some content into it it will always make it as set okay so remember not to use this another interesting thing about set is they are unordered so you cannot use the index so for example in basket I want to access orange I cannot do this basket 0 this is not allowed so that's the basic difference between a list and a set so list allows index operation set doesn't allow a list allows duplicate elements set doesn't allow it and that's one of the primary use case of said that if whenever you want to remove duplicate elements from a list you use set so for example if you have a list of numbers right so I have list of numbers and as you see 2 3 & 4 are repeated so they're duplicate now when you are doing programming you will most frequently encounter this need of removing duplicate elements from a list whenever you face that kind of situation you should always use set and set supports taking lists as an input in the constructor so I am creating a set object here and this is my constructor and I am passing list as an input and it is allowed so when you print unique numbers here you see all the unique numbers in the list okay now as we saw previously if you want to add any new element to that said you can always add it and if you print it it's gonna work fine now often there are needs where you want your set to be frozen frozen meaning you should not be able to change the content of your set in that case you have to use our frozen set so to initialize a frozen set you can use frozen set and you can say in numbers okay so when you print frozen set is gonna print again it did the same thing so frozen set and set are exactly same they are on or the list they remove duplicate as you see here the remove duplicate from this list but the only difference between certain frozen set is it doesn't allow to add a new element so you saw it's not allowing so you cannot change the context or content of your frozen set okay now let's cover some basic operation that asset covers here I have a set called X which has elements ABC it covers it supports in operator you can say a in X will be true but act whatever G in X will be false also if you want to iterate over all the elements then you can use syntax similar to a list so you can say for I in X so it supports I travel I traitor you can alter it over all the elements like this now if you have another set let's say here I have another circle why is having these three elements a G and H right so access this why has this I want to find out a union of these two in basic set theory there are certain common operations such as Union intersection subset etcetera so in Python all of those things are supported to find out Union you can use or operator X or Y so as you see a was common so it's just present one time and then it has all the elements from both sets if you want to find out an intern intersection you use end operation x and y and you see only element common in both the sides is a hence and it printed a you can also find out a difference so you can say X minus y and that's gonna print B and C because from X if you subtract Y is the common element so it will subtract a and what is left is B and C it also supports subset so if you want to check whether X is a subset of Y you can say X less than Y now here of course X is not a subset of Y if a set is a subset of another set it should have the second set should have all the element from the first set so here I'm going to change X set and I'm gonna say okay it has H and G two elements okay and my wife already has H and G now I do X less than Y it's gonna say true okay so that was all about set operations thank you for watching this week