Python: Test if value can be converted to an int in a list comprehension

Question

Basically I want to do this;

return [ row for row in listOfLists if row[x] is int ] 

But row[x] is a text value that may or may not be convertible to an int

I'm aware that this could be done by:

try:     int(row[x]) except:     meh 

But it'd be nice to do it is a one-liner.

Any ideas?

Answer 1

If you only deal with integers, you can use str.isdigit():

Return true if all characters in the string are digits and there is at least one character, false otherwise.

[row for row in listOfLists if row[x].isdigit()] 

Or if negative integers are possible (but should be allowed):

row[x].lstrip('-').isdigit() 

And of course this all works only if there are no leading or trailing whitespace characters (which could be stripped as well).

Answer 2

What about using a regular expression? (use re.compile if needed):

import re ... return [row for row in listOfLists if re.match("-?\d+$", row[x])]