check if input is a number

isnumber.py

#http://stackoverflow.com/questions/354038/how-do-i-check-if-a-string-is-a-number-in-python

def is_number(s):
    try:
        n=str(float(s))
        if n == "nan" or n=="inf" or n=="-inf" : return False
    except ValueError:
        try:
            complex(s) # for complex
        except ValueError:
            return False
    return True