- Sequence Operations 0:57
- Slices 4:29
- Creating Slices 1 objective
- Len, Min, and Max 3:04
- Finding len, min, max 3 objectives
- Membership Testing 2:16
- Count and Index 4:38
- Code Samples: Membership Testing, Count, and Index
- Concatenation and Multiplication 3:04
- Sequence Operations Cheat Sheet
- Recap of Sequence Operations 4 questions
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Membership Testing
2:16Learn how to determine whether your Python sequence contains a particular value or other sequence.
In this video, we'll be discussing
membership testing, in other words,
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whether or not an item or
sequence is inside another sequence.
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Membership testing uses
the operators in and not in.
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Take a look at my workspace here,
you can see I have a really long string,
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really an entire paragraph
from the Python documentation.
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I want to know whether this documentation
excerpt contains the string tuple.
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To find that out,
I can use the operator in.
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The expression, 'tuple' in docs,
will evaluate to true or
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false, true if tuple appears in docs,
and false if it does not.
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You'll see this expression most often
used in conjunction with an if statement.
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So I'm gonna add just a little
bit of code to this, and
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then we're gonna run it
to see what happens.
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Okay, save and run.
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Great, this tells us that the string tuple
is in fact inside this longer string docs.
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Alternatively, we can
use the not in operator.
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This is the opposite of the in operator.
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Not in will return true if the tested
object is not in the sequence, and
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will return false if it is.
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To demonstrate this, I'll modify
our example code just a little bit.
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I'll change the in operator to not in, and
then I'll change our print statements.
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Now when we run this again,
we should see the same result.
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Yes, the string tuple is present
inside the larger string docs.
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That's the gist of membership testing.
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I've demonstrated it here with strings,
but
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these operators work for all sequences.
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See the following instruction step for
code examples showing how to use in and
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not in with lists and tuples as well.
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