Python's filter () function

The filter () function is a high-order function built into Python.

The filter () function accepts a function F and a list, the function of which is to judge each element, return True or False, Filter () Automatically filters out non-conforming elements based on the result of the decision, returning a new list of eligible elements.

Filter () filters out the number of square roots in 1~100 as integers.
The code is implemented in the following way:

Method One: (To find out whether the root is equal to 0)

Import Mathdef is_sqrt (x):   return math.sqrt (x)%1==0print filter (IS_SQRT, range (1, 100))

　　

Method Two: (the value after the radical is forced into the integer type and the original root after the value of comparison, to see if it is equal)

Import Mathdef IS_SQR (x):   y=math.sqrt (x)   return int (y) ==yprint filter (IS_SQRT, Range (1, 101))

　

最终的运行结果：

[1, 4, 9, 16, 25, 36, 49, 64, 81]

　　

Python's filter () function