How to extract numbers from a list of strings?

python, python-2.x, string

Solution

I think you need to process each item in the `list` as a split string on whitespace.

a = ['1 2 3', '4 5 6', 'invalid']
numbers = []
for item in a:
    for subitem in item.split():
        if(subitem.isdigit()):
            numbers.append(subitem)
print(numbers)

['1', '2', '3', '4', '5', '6']

Or in a neat and tidy comprehension:

[item for subitem in a for item in subitem.split() if item.isdigit()]

Problem

How should I extract numbers only from ``` a = ['1 2 3', '4 5 6', 'invalid'] ``` I have tried: ``` mynewlist = [s for s in a if s.isdigit()] print mynewlist ``` and ``` for strn in a: values = map(float, strn.split()) print values ``` Both failed because there is a space between the numbers. Note: I am trying to achieve output as: ``` [1, 2, 3, 4, 5, 6] ```

Original source