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Checking for Membership Using "in" and "not in" Operators (Summary)

Martin Breuss

Checking for Membership Using Python's "in" and "not in" Operators Martin Breuss 01:20

Now you know how to perform membership tests using Python’s in and not in operators. This type of test allows you to check if a given value is present in a collection of values, which is a pretty common operation in programming.

In this video course, you’ve learned how to:

Run membership tests using Python’s in and not in operators
Use the in and not in operators with different data types
Work with operator.contains(), the equivalent function to the in operator
Support in and not in in your own classes

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00:00 Congratulations, you’ve made it to the end of this course on Python’s membership operators in and not in. Before I let you go, let’s do a quick recap of what you’ve learned in this course.

00:10 You can use the in and not in operators to check for membership across many, many data types. The syntax for using it looks the same, but we’ve quickly addressed how membership testing for sequences works a lot slower than membership testing for mappings, for example.

00:26 So you want to stay aware of that. And if you need to do membership checks on large amounts of data, then it’s best to use a mapping such as a set or a dict.

00:34 You first learned that you can do membership checks on iterators, such as a generator, but for generators, stay aware that doing a membership check consumes the generator.

00:44 And finally, you also took a look at custom classes and what you need to do so that your custom class can support membership tests.

00:53 Here’s a couple of additional resources about the different data types that you’ve encountered. You can just click those and there’s often a tutorial as well as a video course.

01:02 You can learn more about lists, tuples, strings,

01:06 dictionary sets, or also if you want to learn more about iterators and iterables, then you can check out the resources we have on the site.

01:14 And that’s it. Thank you for watching. I’m Martin and hope to see you around at Real Python.

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