How do I check if a string is a number (float)?

Question

What is the best possible way to check if a string can be represented as a number in Python?

The function I currently have right now is:

def is_numb         


        

Answer 1

You can generalize the exception technique in a useful way by returning more useful values than True and False. For example this function puts quotes round strings but leaves numbers alone. Which is just what I needed for a quick and dirty filter to make some variable definitions for R.

import sys

def fix_quotes(s):
    try:
        float(s)
        return s
    except ValueError:
        return '"{0}"'.format(s)

for line in sys.stdin:
    input = line.split()
    print input[0], '<- c(', ','.join(fix_quotes(c) for c in input[1:]), ')'