isNumber? check

[Rob Hunter]

How do I check if a value is a number in Python?

One way is (x == type(1)) and (x == type(1.2)) and (x ==
type(2387482734 274)) and ...

but this seems kludgy. Any better way?

Thanks,
Rob

[Peter Otten]

Re: isNumber? check

Rob Hunter wrote:
[color=blue]
> How do I check if a value is a number in Python?[/color]
[color=blue][color=green][color=darkred]
>>> isinstance(1+1j , (float,int,long ,complex))[/color][/color][/color]
True

Peter

[Duncan Booth]

Re: isNumber? check

Rob Hunter <rob@cs.brown.e du> wrote in
news:mailman.10 64844761.11275. python-list@python.org :
[color=blue]
> How do I check if a value is a number in Python?
>
> One way is (x == type(1)) and (x == type(1.2)) and (x ==
> type(2387482734 274)) and ...
>
> but this seems kludgy. Any better way?
>
> Thanks,
> Rob
>
>[/color]

If you really have to test it then use:

isinstance(x, (int, long, float, complex))

but mostly you shouldn't care.

--
Duncan Booth duncan@rcp.co.u k
int month(char *p){return(1248 64/((p[0]+p[1]-p[2]&0x1f)+1)%12 )["\5\x8\3"
"\6\7\xb\1\x9\x a\2\0\4"];} // Who said my code was obscure?

[Terry Reedy]

Re: isNumber? check


"Rob Hunter" <rob@cs.brown.e du> wrote in message
news:mailman.10 64844761.11275. python-list@python.org ...[color=blue]
> How do I check if a value is a number in Python?
>
> One way is (x == type(1)) and (x == type(1.2)) and (x ==
> type(2387482734 274)) and ...
>
> but this seems kludgy. Any better way?[/color]

type(x) in (int, long, float, complex) # or,
isinstance(x, (int, long, float, complex)) # now preferred, I think

But how about x=x-0?
This also accepts a user-defined number-class instance.

This option gets to the point that 'number' is not exactly defined in
either Python or mathematics. So checking for 'numberness' may or may
not be what you need .

Terry J. Reedy

[Miki Tebeka]

Re: isNumber? check

Hello Rob,[color=blue]
> How do I check if a value is a number in Python?
>
> One way is (x == type(1)) and (x == type(1.2)) and (x ==
> type(2387482734 274)) and ...
>
> but this seems kludgy. Any better way?[/color]
Same thing, different way:
from types import IntType, LongType, FloatType
def is_num(n):
return n in (IntType, LongType, FloatType)

HTH.
Miki