python - 在 python 中，如何删除 numpy 3d 数组中每第 n 个元素的一系列列？

Question

与此类似question ，假设我有一个 3D Numpy 数组，为了清楚起见，我在其上方添加了注释标签:

          #C  C  C  R  R  C  C  C  R  R  C  C  C
    a = [[[10,11,12,13,14,15,16,17,18,19,20,21,22],
          [23,24,25,26,27,28,29,30,31,32,33,34,35]],                

         [[36,37,38,39,40,41,42,43,44,45,46,47,48],
          [48,49,50,51,52,53,54,55,56,57,58,59,60]],

         [[61,62,63,64,65,66,67,68,69,70,71,72,73],
          [74,75,76,77,78,79,80,81,82,83,84,85,86]]]

我可以在一行代码中删除标记为R的列吗？因此，从索引 3 开始，每五个元素删除两列。在这种情况下，生成的数组将如下所示:

          #C  C  C  C  C  C  C  C  C
    a = [[[10,11,12,15,16,17,20,21,22],
          [23,24,25,28,29,30,33,34,35]],                

          [[36,37,38,41,42,43,46,47,48],
           [48,49,50,53,54,55,58,59,60]],

          [[61,62,63,66,67,68,71,72,73],
           [74,75,76,79,80,81,84,85,86]]]

我想让代码更加通用，以便它可以处理删除不同大小和位置的 3D 数组中的列对。对于此示例，我可以使用以下命令一次删除一列:

    start = 3
    step = 5
    a = numpy.delete(big, numpy.s_[start:numpy.size(big, 2):step], 2)
    a = numpy.delete(a, numpy.s_[start:numpy.size(a, 2):step - 1], 2)

但是有没有办法指定要删除的列范围，从而用一行代码完成任务？

Answer 1

与 linked posted answer there 非常相似-

In [4]: a[...,np.mod(np.arange(a.shape[-1]),5)<3]
Out[4]: 
array([[[10, 11, 12, 15, 16, 17, 20, 21, 22],
        [23, 24, 25, 28, 29, 30, 33, 34, 35]],

       [[36, 37, 38, 41, 42, 43, 46, 47, 48],
        [48, 49, 50, 53, 54, 55, 58, 59, 60]],

       [[61, 62, 63, 66, 67, 68, 71, 72, 73],
        [74, 75, 76, 79, 80, 81, 84, 85, 86]]])

或更短的 -

a[...,(np.arange(a.shape[-1])%5)<3]

使其通用/参数化 -

group_size = 5
ignore_size = 2
out = a[...,(np.arange(a.shape[-1])%group_size)<(group_size-ignore_size)]