If you only want to extract only positive integers, try the following:

>>> txt = "h3110 23 cat 444.4 rabbit 11 2 dog"
>>> [int(s) for s in txt.split() if s.isdigit()]
[23, 11, 2]

I would argue that this is better than the regex example because you don't need another module and it's more readable because you don't need to parse (and learn) the regex mini-language.

This will not recognize floats, negative integers, or integers in hexadecimal format. If you can't accept these limitations, jmnas's answer below will do the trick.

Without regex:

>>> int(''.join(filter(str.isdigit, a)))
70

Kind of broad, pulling from a text file, but will do for many applications of getting both integers and floats out of strings.

The file, commaseperated.txt has a row looking like this:

Input: (0, 1, 2.4), 1, 5, 8, 99.7, 0.1), (, )()!@!#, 9

    import re


    # a function to pull the numbers from many lists of strings
    def func(a, z, c):
        # -- Read .txt -- #
        filename = 'commaseperated.txt'
        f1 = open(filename, 'r')  # open the file for reading
        data = f1.readlines()  # read the entire file as a list of strings
        f1.close()
        #
        for line in data:
            cells = line.strip().split(',')
            # empty string
            b = ""
            # range through cells of from a text file split by commas
            for i in range(a, len(cells[z:c])+a):
                # no commas in the cells so make dummy commas for new string
                b += cells[i] + ','
            # find all the numbers
            z = re.findall(r'\d+(?:\.\d+)?', b)
            # return a list of floated values from the text string
            return [float(z[s]) for s in range(len(z))]

    Output: [0, 1, 2.4, 1, 5, 8, 99.7, 0.1, 9]