Trying to imitate Excel's SUMPRODUCT function:
SUMPRODUCT(v1, v2, ..., vN) =
v1[0]*v2[0]*...*vN[0] + v1[1]*v2[1]*...*vN[1] + ... + v1[n]*v2[n]*...*vN[n]
where n is the number of elements in each vector.
This is similar to dot product, but for multiple vectors. I read the very detailed discussion of the regular dot product, but I don't know how to cleanly extend it to multiple vectors. For reference, I'm copying the optimized code proposed there, which I ported (trivially) to Python 3. BTW, for dot product, the last approach still wins in P3K.
def d0(v1,v2):
"""
d0 is Nominal approach:
multiply/add in a loop
"""
out = 0
for k in range(len(v1)):
out += v1[k] * v2[k]
return out
def d1(v1,v2):
"""
d1 uses a map
"""
return sum(map(mul,v1,v2))
def d3(v1,v2):
"""
d3 uses a starmap (itertools) to apply the mul operator on an zipped (v1,v2)
"""
return sum(starmap(mul,zip(v1,v2)))
Map the list to create a list of products, and then sum it.
This can be done in one line:
sum(map(lambda Xi, Yi: Xi * Yi, ListX, ListY))
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