Python Data Structures: Sets, Frozensets, and Multisets (Bags)

See how to implement mutable and immutable set and multiset (bag) data structures in Python using built-in data types and classes from the standard library.

A set is an unordered collection of objects that does not allow duplicate elements. Typically sets are used to quickly test a value for membership in the set, to insert or delete new values from a set, and to compute the union or intersection of two sets.

Python and its standard library provide several set implementations with different characteristics:

- The "set" built-in
- The "frozenset" built-in
- The "collections.Counter" class

Watch the video tutorial to see how sets work in general and how to use them in Python.

Articles mentioned in the video:

* * *

[deusvult]

Your tutorials are really like the channel s name .. this one is real python

[encodedCoder]

Wonderful explanation but add time stamps for targeted navigation for viewers

[sto]

Thanks Dan, I recently learnt about this from the docs. Great explanation.

[koodauskanava]

Thanks again. I didn't know about Counters or frozen sets. Really useful stuff! Would be cool to see you making small rpg type game with all these neat Python tricks. I would enjoy watching like a 1 hour video of it.

[bronodude]

You hve not added link to 'what is hashable' that ccanbe added to sets.. Also can you state what is data structure in simple terms?

[picosdrivethru]

Isnt the Counter class really a dictionary with a custom add item protocol defined? (Newb question sorry if its not accurate).. it kind of is right? I forgot multisets exist...

[sehbanomer]

Well I used to call Counter or multiset a freq_dist

[pnw_dev]

Is there a compelling reason to use a Counter over a vanilla dictionary other than convenience/syntactical sugar? That .update() function is pretty slick

[mehdizyoutube]

Quick question: Isn't Multi-Bags example a 'dict' type, and not 'set()' ?

[clearlyajit]

Is this IDLE or something else? Because I love its theme!

[gcasanas]

As a general question. What would be the pythonic way to express the following:



or...

journal_entry = user_input(cmd)

[impuresilver]

Is this how websites store user accounts? Seems like it can in a way.

[Danielagostinho]

Hey Dan!

Is there a way to have lists on a set besides getting a tuple version of those lists and append it to the set?