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[英]How to subtract every first column value form every other values from a file?
[英]How to subtract the first column from every column of an array
我正在做非常简单的减法,但我做错了。 我想从数组的每一列中减去第一列。 例如:
winner=
[1,2,3]
[2,3,5]
[3,5,7]
我想得到这样的结果:
[0,1,2]
[0,1,3]
[0,2,4]
这是错误,我不知道该怎么做。
winner.shape
(5, 3)
winner_difference=winner-winner[:,0]
winner_difference
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
<ipython-input-69-d385252ef2de> in <module>
----> 1 winner_difference=winner-winner[:,0].T
2 winner_difference
ValueError: operands could not be broadcast together with shapes (5,3) (5,)
用列表推导来实现这是一件非常简单的事情。
>>> winner = [[1,2,3], [2,3,5], [3,5,7]]
>>> [[y - x[0] for y in x] for x in winner]
[[0, 1, 2], [0, 1, 3], [0, 2, 4]]
>>>
我相信您正在寻找:
winner - np.vstack(winner[0])
一种更有效的方法,利用 numpy 广播:
output = winner - winner[:, [0]]
Output:
>>> output
array([[0, 1, 2],
[0, 1, 3],
[0, 2, 4]])
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