How to extract numbers from filename in Python?

Question

I need to extract just the numbers from file names such as:

GapPoints1.shp

GapPoints23.shp

GapPoints109.shp

How can I extract just the numbers from these files using Python? I'll need to incorporate this into a for loop.

Answer 1

you can use regular expressions:

regex = re.compile(r'\d+')

Then to get the strings that match:

regex.findall(filename)

This will return a list of strings which contain the numbers. If you actually want integers, you could use int:

[int(x) for x in regex.findall(filename)]

If there's only 1 number in each filename, you could use regex.search(filename).group(0) (if you're certain that it will produce a match). If no match is found, the above line will produce a AttributeError saying that NoneType has not attribute group.