[英]Upper diagonal of a 2D numpy array
这看起来很简单(并且编写三行循环很简单),但是如何使用numpy切片创建numpy数组的上对角线的索引位置列表? 即
给定一个4x4数组,我想要X的索引位置:
[ X X X X ]
[ 0 X X X ]
[ 0 0 X X ]
[ 0 0 0 X ]
赠送:
[ (0,0), (0,1), (0,2), (0,3), (1,1), (1,2), (1,3), (2,2), (2,3), (3,3) ]
carnieri打败了我的numpy.triu_indices
答案,但也有numpy.triu_indices_from
将数组作为输入而不是维度。
虽然索引位置的格式不同,但您似乎想要函数numpy.triu_indices
。
如果您正在运行Ubuntu并且不想仅为此升级Numpy,则可以使用以下函数:
from itertools import chain
triu_indices = lambda x, y=0: zip(*list(chain(*[[(i, j) for j in range(i + y, x)] for i in range(x - y)])))
例:
In [26]: triu_indices = lambda x, y=0: zip(*list(chain(*[[(i, j) for j in range(i + y, x)] for i in range(x - y)])))
In [27]: triu_indices(4)
Out[27]: [(0, 0, 0, 0, 1, 1, 1, 2, 2, 3), (0, 1, 2, 3, 1, 2, 3, 2, 3, 3)]
In [28]: zip(*triu_indices(4))
Out[28]:
[(0, 0),
(0, 1),
(0, 2),
(0, 3),
(1, 1),
(1, 2),
(1, 3),
(2, 2),
(2, 3),
(3, 3)]
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.