Python3 filter() Function
Python3 Built-in FunctionsDescription
filter()The function is used to filter sequences, filtering out elements that do not meet the conditions, and returns an iterator object. If you want to convert it to a list, you can uselist()to convert.
It accepts two parameters: the first is a function, the second is a sequence. Each element of the sequence is passed to the function as a parameter for judgment, which then returns True or False. Finally, the elements that return True are placed into a new list.
Syntax
The following is the syntax of the filter() method:
filter(function, iterable)
Parameters
- function -- judgment function.
- iterable -- iterable object.
Return Value
Returns an iterator object
Example
The following shows an example of using the filter function:
Filter out all odd numbers in the list:
#!/usr/bin/python3
def is_odd(n):
return n % 2 == 1
tmplist = filter(is_odd, [1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
newlist = list(tmplist)
print(newlist)
Output result:
[1, 3, 5, 7, 9]
Filter out numbers from 1 to 100 whose square root is an integer:
#!/usr/bin/python3
import math
def is_sqr(x):
return math.sqrt(x) % 1 == 0
tmplist = filter(is_sqr, range(1, 101))
newlist = list(tmplist)
print(newlist)
Output result:
[1, 4, 9, 16, 25, 36, 49, 64, 81, 100]Other Extensions