Filter
Filter
First: What is 'filter'?
In very short, filter runs the given function over the given iterable and only returns those that are true.
For example: We have a function that returns only those items in the list that are integers.
The Syntax
filter(function, iterable)
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The function can be a function or a lambda expression.
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The iterable can be any iterable - list, string, etc.
A few examples:
All these examples use this list: list = [1, 2, 3,"A", 11, "C", 12, 13, 14]
1. filter(lambda x: type(x) is str, list)
['A', 'C']
2. filter(lambda x: x<10, list)
[1, 2, 3]
3. filter(lambda x: type(x) is int, list)
[1, 2, 3, 11, 12, 13, 14]
4. filter(lambda x: type(x) is int and int(x)%2==0, list)
[2, 12, 14]
5. filter(lambda x: x%2==0, filter(lambda x: type(x) is int, list))
The inner filter returns all integers as a list. then the outer filter runs on that filtered list.
[2, 12, 14]