更新时间:2022-11-09 23:33:09
我们可以计算线性索引,然后累加到使用 np.add.at
.因此,以xpos
和ypos
作为数组,这是一个实现-
We could compute the linear indices, then accumulate into zeros-initialized output array with np.add.at
. Thus, with xpos
and ypos
as arrays, here's one implementation -
m,n = xpos.max()+1, ypos.max()+1
out = np.zeros((m,n),dtype=int)
np.add.at(out.ravel(), xpos*n+ypos, 1)
样品运行-
In [95]: # 1d arrays holding x and y indices
...: xpos = np.array([0,0,1,2,1,2,1,0,0,0,0,1,1,1,2,2,3])
...: ypos = np.array([3,2,1,1,3,0,1,0,0,1,2,1,2,3,3,2,0])
...:
In [96]: cnt_a = np.zeros((4,4))
In [97]: # This method works, but is very slow for a large array
...: for i in range(0,len(xpos)):
...: cnt_a[xpos[i],ypos[i]] = cnt_a[xpos[i],ypos[i]] + 1
...:
In [98]: m,n = xpos.max()+1, ypos.max()+1
...: out = np.zeros((m,n),dtype=int)
...: np.add.at(out.ravel(), xpos*n+ypos, 1)
...:
In [99]: cnt_a
Out[99]:
array([[ 2., 1., 2., 1.],
[ 0., 3., 1., 2.],
[ 1., 1., 1., 1.],
[ 1., 0., 0., 0.]])
In [100]: out
Out[100]:
array([[2, 1, 2, 1],
[0, 3, 1, 2],
[1, 1, 1, 1],
[1, 0, 0, 0]])