Python Numpy结构化数组(recarray)将值分配到切片中 [英] Python Numpy Structured Array (recarray) assigning values into slices

问题描述

以下示例显示了我想做什么:

The following example shows what I want to do:

>>> test
rec.array([(0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0),
   (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0)], 
  dtype=[('ifAction', '|i1'), ('ifDocu', '|i1'), ('ifComedy', '|i1')])

>>> test[['ifAction', 'ifDocu']][0]
(0, 0)

>>> test[['ifAction', 'ifDocu']][0] = (1,1)
>>> test[['ifAction', 'ifDocu']][0]
(0, 0)

因此，我想将值(1,1)分配给test[['ifAction', 'ifDocu']][0]. (最终，我想做类似test[['ifAction', 'ifDocu']][0:10] = (1,1)的事情，为0:10分配相同的值.我尝试了很多方法，但从未成功.有什么方法可以做到这一点?

So, I want to assign the values (1,1) to test[['ifAction', 'ifDocu']][0]. (Eventually, I want to do something like test[['ifAction', 'ifDocu']][0:10] = (1,1), assigning the same values for for 0:10. I have tried many ways but never succeeded. Is there any way to do this?

谢谢你， 琼

推荐答案

当您说test['ifAction']时，您将看到数据视图. 当您说test[['ifAction','ifDocu']]时，您正在使用花式索引，因此会获得数据的副本.副本无济于事，因为修改副本会使原始数据保持不变.

When you say test['ifAction'] you get a view of the data. When you say test[['ifAction','ifDocu']] you are using fancy-indexing and thus get a copy of the data. The copy doesn't help you since modifying the copy leaves the original data unchanged.

因此，一种解决方法是分别为test['ifAction']和test['ifDocu']分配值:

So a way around this is to assign values to test['ifAction'] and test['ifDocu'] individually:

test['ifAction'][0]=1
test['ifDocu'][0]=1

例如:

import numpy as np
test=np.rec.array([(0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0),
   (0, 0, 0), (0, 0, 0), (0, 0, 0), (0, 0, 0)], 
  dtype=[('ifAction', '|i1'), ('ifDocu', '|i1'), ('ifComedy', '|i1')])

print(test[['ifAction','ifDocu']])
# [(0, 0) (0, 0) (0, 0) (0, 0) (0, 0) (0, 0) (0, 0) (0, 0) (0, 0) (0, 0)]
test['ifAction'][0]=1
test['ifDocu'][0]=1

print(test[['ifAction','ifDocu']][0])
# (1, 1)
test['ifAction'][0:10]=1
test['ifDocu'][0:10]=1

print(test[['ifAction','ifDocu']])
# [(1, 1) (1, 1) (1, 1) (1, 1) (1, 1) (1, 1) (1, 1) (1, 1) (1, 1) (1, 1)]

要深入了解，请参见这篇文章罗伯特·克恩(Robert Kern).

这篇关于Python Numpy结构化数组(recarray)将值分配到切片中的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！