[英]Shuffle ordering of some rows in numpy array
I want to shuffle the ordering of only some rows in a numpy array. 我想在numpy数组中只调整一些行的顺序。 These rows will always be continuous (eg shuffling rows 23-80).
这些行将始终是连续的(例如,洗牌行23-80)。 The number of elements in each row can vary from 1 (such that the array is actually 1D) to 100.
每行中的元素数量可以从1(使得数组实际为1D)变为100。
Below is example code to demonstrate how I see the method shuffle_rows()
could work. 下面是示例代码,演示我如何看待
shuffle_rows()
方法可以工作。 How would I design such a method to do this shuffling efficiently? 我如何设计这样一种方法来有效地进行洗牌?
import numpy as np
>>> a = np.arange(20).reshape(4, 5)
>>> a
array([[ 0, 1, 2, 3, 4],
[ 5, 6, 7, 8, 9],
[10, 11, 12, 13, 14],
[15, 16, 17, 18, 19]])
>>> shuffle_rows(a, [1, 3]) # including rows 1, 2 and 3 in the shuffling
array([[ 0, 1, 2, 3, 4],
[15, 16, 17, 18, 19],
[ 5, 6, 7, 8, 9],
[10, 11, 12, 13, 14]])
You can use np.random.shuffle
. 您可以使用
np.random.shuffle
。 This shuffles the rows themselves, not the elements within the rows. 这会对行本身进行混洗,而不是行中的元素。
This function only shuffles the array along the first index of a multi-dimensional array
此函数仅沿多维数组的第一个索引对数组进行混洗
As an example: 举个例子:
import numpy as np
def shuffle_rows(arr,rows):
np.random.shuffle(arr[rows[0]:rows[1]+1])
a = np.arange(20).reshape(4, 5)
print(a)
# array([[ 0, 1, 2, 3, 4],
# [ 5, 6, 7, 8, 9],
# [10, 11, 12, 13, 14],
# [15, 16, 17, 18, 19]])
shuffle_rows(a,[1,3])
print(a)
#array([[ 0, 1, 2, 3, 4],
# [10, 11, 12, 13, 14],
# [15, 16, 17, 18, 19],
# [ 5, 6, 7, 8, 9]])
shuffle_rows(a,[1,3])
print(a)
#array([[ 0, 1, 2, 3, 4],
# [10, 11, 12, 13, 14],
# [ 5, 6, 7, 8, 9],
# [15, 16, 17, 18, 19]])
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