In Python, how do I determine if an object is iterable?

Question

Is there a method like isiterable? The only solution I have found so far is to call

hasattr(myObj, \'__iter__\')

But I am not

Answer 1

Instead of checking for the __iter__ attribute, you could check for the __len__ attribute, which is implemented by every python builtin iterable, including strings.

>>> hasattr(1, "__len__")
False
>>> hasattr(1.3, "__len__")
False
>>> hasattr("a", "__len__")
True
>>> hasattr([1,2,3], "__len__")
True
>>> hasattr({1,2}, "__len__")
True
>>> hasattr({"a":1}, "__len__")
True
>>> hasattr(("a", 1), "__len__")
True

None-iterable objects would not implement this for obvious reasons. However, it does not catch user-defined iterables that do not implement it, nor do generator expressions, which iter can deal with. However, this can be done in a line, and adding a simple or expression checking for generators would fix this problem. (Note that writing type(my_generator_expression) == generator would throw a NameError. Refer to this answer instead.)

You can use GeneratorType from types:

>>> import types
>>> types.GeneratorType

>>> gen = (i for i in range(10))
>>> isinstance(gen, types.GeneratorType)
True

--- accepted answer by utdemir

(This makes it useful for checking if you can call len on the object though.)