Usage of the filter () function in Python, pythonfilter

Usage of the filter () function in Python, pythonfilter

The built-in filter () function of Python is used to filter sequences.

Similar to map (), filter () also receives a function and a sequence. When it is different from map (), filter () applies the input function to each element in sequence, and determines whether to retain or discard the element based on whether the returned value is True or False.

For example, to delete an even number in a list, only the odd number is retained. You can write this statement:

Def is_odd (n): return n % 2 = 1 filter (is_odd, [1, 2, 4, 5, 6, 9, 10, 15]) # result: [1, 5, 9, 15]

Delete an empty string from a sequence, which can be written as follows:

Def not_empty (s): return s and s. strip () filter (not_empty, ['A', '', 'B', None, 'C','']) # result: ['A ', 'B', 'C']

Obviously, the key to using the filter () function is to implement a "filter" function correctly.
Exercise

Please try to delete 1 ~ with filter ~ The prime number of 100.