It really feels now like you are TRYING to miss the point of equality and
identity, and why 'is None' checks are the correct approach to recommend.
Here's a slightly contrived, but not absurd function. I've certainly
written a great many that follow this general form.
>>> def add_multiples(elements=None, multiples=None):
... if elements == None:
... # Default to the intergers 1 to 10
... elements = list(range(1, 11))
... if multiples == None:
... multiples = [1] * len(elements)
... total = 0
... for e, m in zip(elements, multiples):
... total += e*m
... return total
...
>>> a = [13, 27, 52]
>>> b = [1, 2, 3]
>>> add_multiples(a, b)
223
>>> add_multiples()
55
I was just reading something that mentioned the famous Gauss sum of
sequential numbers :-).
We can try this with other sequences of numbers where it should succeed
(and DOES if I use the clear and obvious approach rather than deliberately
confusing identity and equality):
>>> c = np.array([13, 27, 52])
>>> d = range(1, 1000)
>>> add_multiples(c, d)
Traceback (most recent call last):
File "<ipython-input-38-c4826ecd2a2e>", line 1, in <module>
add_multiples(c, d)
File "<ipython-input-8-8c58e2c77071>", line 2, in add_multiples
if elements == None:
ValueError: The truth value of an array with more than one element is
ambiguous. Use a.any() or a.all()
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