Python - Apply function over pairwise elements of array without using loops

Question

Suppose I want to apply a function func over the pairwise elements of a numpy array A, and I want to produce an a new matrix M, where M[i,j] = func(A[i],A[j]) . Is there someway to do this in Python without using loops?

Answer 1

Yes, simply something like this (assuming your func is a nice numpy friendly function):

A = np.arange(5)

def f(x,y):
    return x+2*y

X,Y = np.meshgrid(A,A)

M = f(X,Y)

If not numpy friendly you may want to look at np.vectorize .