Is there a way to output the numbers only from a python list?

This should be the most efficient and shortest in Python 2:

import operator
filter(operator.isNumberType, list_1)

This in Python 3:

import numbers
[x for x in list_1 if isinstance(x, numbers.Number)]

List comprehensions.

list_2 = [num for num in list_1 if isinstance(num, (int,float))]