Python-3.4.3/C3/Sets-in-Python/English-timed

Time	Narration
00:01	Welcome to the spoken tutorial on Sets in Python.
00:06	In this tutorial, you will learn to, Create sets from lists
00:12	Perform union, intersection and symmetric difference operations
00:18	Check if a set is a subset of other and Understand various similarities with lists
00:27	To record this tutorial, I am using Ubuntu Linux 16.04 operating system
00:35	Python 3.4.3 and IPython 5.1.0
00:42	To practise this tutorial, you should know how to run basic Python commands on the ipython console and use lists
00:53	If not, see the relevant Python tutorials on this website.
00:58	First let us see the overview of sets.
01:02	Sets are unordered collections of unique elements.
01:07	The set itself is mutable. We can add or remove items from it.
01:14	Let us start ipython. Open the terminal.
01:19	Type ipython3 and press Enter.
01:24	From here onwards, remember to press the Enter key after typing every command on the terminal.
01:31	Let us look at how to input sets.
01:35	Type, a underscore list is equal to inside square brackets 1 comma 2 comma 1 comma 4 comma 5 comma 6 comma 2
01:47	Type, a is equal to set inside brackets a underscore list
01:54	Then type, a
01:57	We can see that duplicates are removed and the set contains only unique elements.
02:03	Sets can also be created directly as follows
02:08	Type, b is equal to inside curly braces 1 comma 2 comma 1 comma 4 comma 5 comma 6 comma 2
02:19	Type, b. As before, we see that the set contains only unique elements.
02:27	To create an empty set, type, c is equal to set open and close brackets
02:36	Note that d is equal to open and close curly braces creates an empty dictionary, not an empty set.
02:45	Sets can contain numbers, strings and tuples. But cannot contain mutable elements such as lists or dictionaries.
02:56	Type, b underscore list is equal to inside square brackets again inside square brackets 1 comma 2 comma 1 comma 6 comma 2
03:09	Now type, b is equal to set inside brackets b underscore list
03:17	As you can see, it gives a TypeError.
03:21	Now let us perform some operations on sets. For this, we will first create a pair of sets.
03:29	Type the sets as shown.
03:33	Here, f is the set of fibonacci numbers from 1 to 10.
03:39	And p is the set of prime numbers from 1 to 15.
03:44	Various operations can be performed on sets.
03:47	First we will add an element to a set by using add method.
03:53	Type, f dot add inside brackets 13
03:58	Now type, f As you can see, 13 is added to the set f.
04:06	add method has no effect if the element is already present.
04:11	Type, f dot add inside brackets 13
04:16	Type, f As you can see, 13 is not added this time.
04:23	Next we will learn to remove an element using remove method.
04:28	Type, p dot remove inside brackets 13
04:34	Now type, p. As you can see, 13 is removed from the set p.
04:41	If the element is not a member, it raises a KeyError.
04:46	Type, p dot remove inside brackets 18
04:52	KeyError is raised since element 18 is not present in p.
04:57	The pipe character stands for union.
05:01	Type, f pipe p
05:06	Or type, f dot union inside brackets p It gave the union of f and p
05:16	The ampersand character stands for intersection.
05:20	Type, f ampersand p Or type, f dot intersection inside brackets p
05:30	It gave the intersection of f and p.
05:34	Type, f minus p Or type, f dot difference inside brackets p
05:44	It gave all the elements that are in f but not in p.
05:50	Type, f caret p
05:54	Or type, f dot symmetric underscore difference inside brackets p
06:01	It gives all the elements in f union p but not in f intersection p.
06:08	In mathematical terms, it gives the symmetric difference.
06:13	Sets also support checking of subsets.
06:17	Type, a is equal to set inside brackets inside square brackets 1 comma 2 comma 3 comma 4
06:27	Type, b is equal to set inside brackets inside square brackets 1 comma 2
06:35	Now type, b less than or equal to a Or type, b dot issubset inside brackets a
06:47	It gives True since b is a subset of a.
06:52	Sets also support checking of supersets. Type, b greater than or equal to a
07:01	Or type, b dot issuperset inside brackets a
07:08	We get False since b is not a superset of a.
07:14	Every set is a subset as well as a superset of itself.
07:20	Type, a less than or equal to a a greater than or equal to a
07:28	It gives True in both cases since a is a superset and subset of itself.
07:35	Elements of a set can be accessed using for loop.
07:39	Type, for x in a colon print inside brackets x
07:47	The items from the set will not appear in any specific order.
07:52	The length and containership check on sets are similar as in lists and tuples.
07:59	Type, len inside brackets a It shows 4.
08:07	Type, 1 in a 7 in a
08:13	It prints True and False respectively
08:18	Sets do not support indexing. Hence, slicing and striding are not valid on sets.
08:25	Pause the video. Try this exercise and then resume the video.
08:31	Given a list of marks, as shown, list all the duplicate marks.
08:37	Switch to the terminal for the solution.
08:41	Type, marks is equal to inside square brackets 20 comma 23 comma 22 comma 23 comma 20 comma 21 comma 23
08:53	marks underscore set is equal to set inside brackets marks
09:00	for num in marks underscore set colon marks dot remove inside brackets num
09:10	remove method only removes the first occurrence of an element from the list.
09:17	Type, duplicates is equal to set inside bracket marks
09:24	Now type, duplicates
09:28	We now have duplicate marks in the set duplicates. Hence, we have obtained our required solution.
09:37	This brings us to the end of this tutorial. Let us summarize.
09:43	In this tutorial, we have learnt to, Make sets from lists or by using curly braces
09:50	Perform union, intersection and symmetric difference operations
09:55	Check if a set is a subset of other using the less than or equal to operator
10:02	Understand the various similarities with lists like length and containership
10:08	Here are some self assessment questions for you to solve.
10:12	First. If a is assigned as follows, what is set of a
10:18	Second. Given odd and squares as shown. How do you find the symmetric difference of these two sets?
10:27	Third. If a is a set, how do you check if a variable b exists in a?
10:34	And the answers, First. set of a will have all the common elements in the list a, that is 1 comma 2 comma 3 comma 5 comma 8.
10:46	Second. To find the symmetric difference between two sets, we use the operator caret. So we can type odd caret squares
10:56	Third. To check the containership, we type, b in a
11:01	Please post your timed queries in this forum.
11:05	Please post your general queries on Python in this forum.
11:10	FOSSEE team coordinates the TBC project.
11:15	Spoken Tutorial Project is funded by NMEICT, MHRD, Govt. of India. For more details, visit this website.
11:25	This is Priya from IIT Bombay signing off. Thanks for watching.

Contributors and Content Editors

PoojaMoolya