Python Tutorial - 24. Sets and Frozen Sets

Key Takeaways

hello and welcome to core Basics coding tutorial 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 learned 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 a set in Python so this is how I do it you should use C brackets right and then you should add all your elements in the sent uh in this set so I have bunch of fruits that I have placed in my basket I love I like I love mango by the way it's summer and India uh there are a lot of mangoes coming out and they taste so good and then I have some repeated element so I have two apples 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 set now let's print the content of basket when I do that you notice that uh orange was present two times in my basket but this one is just showing one time so that's what unique element aspect means uh a set doesn't allow duplicate elements so it will remove duplicates automatically so set could be useful when you want to have only unique elements uh for doing anything okay there is another way to initialize set which is by doing this so you can just initialize set like this and then you can add the elements into it so for example I'm going to add whatever number B do add so a do add okay when I print a I get one and two all right now when you initialize the set using the first syntax which is cly brackets remember that you don't use um empty cly brackets because when you do that it is going to initialize it as dictionary you see this uh and if I have a is equal to something if I have as long as I have some content into it it will always always make it a set okay so remember not to use this another interesting thing about set is um they are unordered so you cannot use the index so for example in basket I want to access orange I cannot do this basket zero this is not as allowed so that's the basic difference between a list and a set so list allows index operation set doesn't allow it list allows duplicate elements set doesn't allow it and that's one of the primary use case of set that 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 three and four are repeated so they are duplicate now when you're are doing programming you will most frequently encounter this need of REM removing duplicate elements from a list whenever you uh face that kind of situation you should always use set and set supports taking list as an input in the Constructor so I'm creating a set object here and this is my Constructor and I'm passing list as an input and it is allowed so when you print uh unique numbers here you will see all the unique numbers in the list okay now as we saw previously if you want to add any new element to that uh s you can always add it and if you print it it's going to uh 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 uh you have to use a frozen set so to initialize a frozen set you can use frozen set and you can say numbers okay so when you print Frozen set is going to print again it did the same thing so Frozen set and set are exactly same they are unorder list they removed duplicate as you see here they removed duplicate from this list uh but the only difference between set and 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 of uh content of uh your Frozen set okay now let's cover some basic operations that uh a set covers uh here I have a set called X which has elements a b c uh it covers it supports um in operator so you can say a in X will be true but uh 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 4 I in X so it supports iterable iterator you can iterate over all the elements like this now if you have another set uh let's say here I have another set called Y is having these three elements AG and H right so X has this y has this I want to find out a union of these two right in in in in basic set theory there are certain common operations such as Union intersection subset Etc so in Python all of those things are supported uh to find out Union you can use our operator X or Y so as you see a was common so is just present one time and then it has all the elements from both the sets if you want to find out an inter intersection you use end Operation X and Y and you see only element common in both the sets is a hence it printed a you can also find out a difference so you can say x - Y and that's going to print B and C because from X if you subtract y a 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 elements from the first set so here I'm going to change X set and I'm going to say okay it has H and G two elements okay and my y already has H and G now I do X less than y it's going to say true okay so that was all about set operations thank you for watching this video