On Tue, 03 Nov 2009 10:22:28 -0500, J Kenneth King wrote: > However in this case the procedure by which we derive the value is not > important or even interesting. It is much more succinct to think of the > operation as a value and express it accordingly. There's no need to > clutter the mind with extra name bindings and iteration keywords. They > won't make our idea any more clear. > > dot_product = map(mul, vec1, vec2) > > vs > > dot_product = [a * b for a, b in zip(vec1, vec2)] > > It's very clear, at least to me, what a dot-product is in this case.
Except it's not. The dot product of two vectors returns a scalar, not another vector: http://en.wikipedia.org/wiki/Dot_product So what you want is: dot_product = sum(map(mul, vec1, vec2)) > Adding in the loop construct and name bindings doesn't enhance my > understanding of what a dot-product is. I don't need to see the loop > construct at all in this case. A dot product is simply the > multiplication of each element in a vector sequence. What you need is to define a function dot-product, and not hijack the name for a local value. Then the function's implementation is irrelevant to you: it could use a list comp, or could use map, it could use a for- loop, a while loop, recursion, or black magic: scalar = dot_product(vec1, vec2) -- Steven -- http://mail.python.org/mailman/listinfo/python-list
