How to determine the datatype in Python?

Question

astring ('a','tuple')

How do I determine if "x" is a tuple or string?

score 8 · Accepted Answer · edited May 23 '17 at 12:14

8

if isinstance(x, basestring):
   # a string
else:
   try: it = iter(x)
   except TypeError:
       # not an iterable
   else:
       # iterable (tuple, list, etc)

@Alex Martelli's answer describes in detail why you should prefer the above style when you're working with types in Python (thanks to @Mike Hordecki for the link).

edited May 23 '17 at 12:14

Community

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answered Dec 13 '09 at 11:45

jfs

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+1, `isinstance(x, str)` and `type(x) is str` are both wrong as they don't handle unicode. Also, `isinstance()` is preferred over `type()` since it handles subclasses. – Ayman Hourieh Dec 13 '09 at 11:52

Mike Hordecki · Answer 2 · 2009-12-13T12:38:51.450

5

isinstance(x, str)
isinstance(x, tuple)

In general:

isinstance(variable, type)

Checks whether variable is an instance of type (or its subtype) (docs).

PS. Don't forget that strings can also be in unicode (isinstance(x, unicode) in this case) (or isinstance(x, basestring) (thanks, J.F. Sebastian!) which checks for both str and unicode).

edited Dec 13 '09 at 12:38

answered Dec 13 '09 at 11:43

Mike Hordecki

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The str vs. unicode distinction disappears in Python 3 - unicode and str are now just str. – PaulMcG Dec 13 '09 at 16:15

score 0 · Answer 3 · edited May 06 '15 at 20:58

0

use isinstance(), general syntax is:

if isinstance(var, type):
    # do something

edited May 06 '15 at 20:58

Markus Amalthea Magnuson

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answered Dec 13 '09 at 12:47

Ahmad Dwaik

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How to determine the datatype in Python?

3 Answers3