Comments on: Determine Whether a String Value is Numeric in Python

By: File077

File077 — Fri, 25 Jun 2010 12:27:19 +0000

Wow guys..

def is_numeric(val):
try:
float(val)
except ValueError, e:
return False
return True

“.-02″ FALSE
“-.02″ TRUE
“.02.” FALSE
“02.-” FALSE
“0.00″ True
“-1.2″ TRUE

By: admin

admin — Sat, 17 Apr 2010 03:08:12 +0000

That’s true. Good point. However, I have never come across such values in practice. I think the point of all of this is that you have to evaluate your needs for a given task, and sometimes a simple but unconventional approach can do the trick. Sometimes we may want to sacrifice accuracy for speed. And vice versa.

By: anvesh

anvesh — Fri, 16 Apr 2010 23:48:15 +0000

I would consider this case as not working. This is a false positive. The test passes even though it shouldn’t.

isnumeric(“.-2″) // True

similarly

“2.22.2-”

By: admin

admin — Fri, 16 Apr 2010 23:43:51 +0000

Anvesh, in the post I mention it may not work for all cases. But I don’t know of any cases where it wouldn’t work. Do you? If so, I could tweak the code to handle those possibly.

By: anvesh

anvesh — Fri, 16 Apr 2010 20:06:05 +0000

whatever works for you, I prefer the one that is correct all the time and not just in most cases.

And what do you mean by “extremely slow”? is it taking a min or an hour? I doubt that, the time difference is almost unnoticeable unless you are doing thousands of checks.

By: xavisimsa

xavisimsa — Fri, 16 Apr 2010 15:59:53 +0000

def isnumeric(value):
try:
int(value)
return True
except:
return False

it works perfect, but there is a big problem…it is extremely slow…

the first option is really fast

By: anvesh

anvesh — Mon, 05 Apr 2010 09:41:05 +0000

def isnumeric(value):
try:
int(value)
return True
except:
return False