The argmax function is very useful, it returns the index of the (first)
maximal element of an array. The easiest way to use this is to import numpy,
but numpy is a very large module. We can write a similar function using the
builtin max function with its key argument.
def argmax(x):
return max(range(len(x)), key=lambda i: x[i])Here, the first argument of max is a list from 0 to len(x), and the key
argument gives the max function a function to use to make comparisons and
return the largest element. In this case, the key function maps indices of
the list x to the elements of x, and then returns the index associated with
the largest element of x, which is exactly what we want.