Check if variable is defined with Numpy array?

Question

Sometimes I have a situation where I want to test whether a variable is 0 or None or not. In pure Python, this is simply

foo == True

but when foo is possibly a Numpy object (such as numpy.ndarray), this does not work anymore and I get the error:

ValueError: The truth value of an array with more than one element is ambiguous. 
 Use a.any() or a.all()

and in this case I want a.any(), however this fails on non-iterable objects.

Of course I can explicitly check if foo is 0 or None, but I am wondering if there is a more elegant way to do this.

How can I check if an arbitrary object (both iterable and not) is True or not?

Answer 1

Just use np.all or np.any instead of the .all method. np.all will create an array if it is not one yet.