how to tell a variable is iterable but not a string

Question

I have a function that take an argument which can be either a single item or a double item:

def iterable(arg)
    if #arg is an iterable:
        print \"yes         


        

Answer 1

As of 2017, here is a portable solution that works with all versions of Python:

#!/usr/bin/env python
import collections
import six


def iterable(arg):
    return (
        isinstance(arg, collections.Iterable) 
        and not isinstance(arg, six.string_types)
    )


# non-string iterables    
assert iterable(("f", "f"))    # tuple
assert iterable(["f", "f"])    # list
assert iterable(iter("ff"))    # iterator
assert iterable(range(44))     # generator
assert iterable(b"ff")         # bytes (Python 2 calls this a string)

# strings or non-iterables
assert not iterable(u"ff")     # string
assert not iterable(44)        # integer
assert not iterable(iterable)  # function