Question

I have a python function which uses a regular expression to match one (the first) floating point number in a given string and return the number.

How can I modify it (the regex) to generalize the function so that it returns instead a list with the all numbers in the string?

Here is a working demonstration:

    import re

    def extract_number(s,notfound='NOT_FOUND'):
        regex='[-+]?[0-9]*\.?[0-9]+([eE][-+]?[0-9]+)?' # matching any floating point number 
        m = re.search(regex,s)
        if(m): val=m.group()
        else: val=notfound
        return val

    example='bla1.23bar4.5fuzz6.7cat8'

    print example
    print extract_number(example)

In this example, the output is:

bla1.23bar4.5fuzz6.7cat8
1.23

The modified function which I am looking for, let’s call it extract_numbers (note the plural !), should output this:

bla1.23bar4.5fuzz6.7cat8
[1.23, 4.5, 6.7, 8]

Answer 1

Just use re.findall:

def extract_number(s,notfound='NOT_FOUND'):
    regex=r'[-+]?[0-9]*\.?[0-9]+(?:[eE][-+]?[0-9]+)?'
    return re.findall(regex,s)