Increment Numpy multi-d array with repeated indice

问题:

I'm interested in the multi-dimensional case of Increment Numpy array with repeated indices.

I have an N-dimensional array and a set N index arrays, who's values I want to increment. The index arrays might have have repeated entries.

Without repeats, the solution is

a = arange(24).reshape(2,3,4)
i = array([0,0,1])
j = array([0,1,1])
k = array([0,0,3])
a[i,j,k] += 1

With repeats, (ex. j=array([0,0,2]) ), I'm unable to make numpy increment the replicates.

回答1:

How about this:

import numpy as np
a = np.zeros((2,3,4))
i = np.array([0,0,1])
j = np.array([0,0,1])
k = np.array([0,0,3])

ijk = np.vstack((i,j,k)).T
H,edge = np.histogramdd(ijk,bins=a.shape)
a += H  

回答2:

I don't know if there is an easier solution with direct array indexing, but this works:

for x,y,z in zip(i,j,k):
    a[x,y,z] +=1