用从索引到另一个的值填充numpy矩阵 [英] Fill numpy matrix with values from an index to another

问题描述

我的问题是用从索引到另一个索引的值填充一个numpy矩阵.

My question is about filling a numpy matrix with values from an index to another.

例如，我有这个矩阵:

> mat = np.zeros((0,5))

> mat
  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

例如，假设我要在第一列的第1行到第3列填充mat，值是:1，所以它看起来像这样:

For example, Let's say I want to fill mat from row 1 to 3 at the first column with value : 1 so it will look like this :

> mat
  0 0 0 0 0
  1 0 0 0 0
  1 0 0 0 0
  1 0 0 0 0
  0 0 0 0 0

这是我尝试过的方法，但是这里将1应用于所有列而不是一个列:

Here's what I have tried but here 1 is applied to all the columns instead of one column :

mat[1:3][1]=1

这是什么问题?

推荐答案

有两个问题:

首先，您没有创建所需的矩阵. np.zeros((0,5))将不起作用.您应该改用mat = np.zeros((5,5)).

first of all, you don't create the desired matrix. np.zeros((0,5)) will not work. You should try mat = np.zeros((5,5)) instead.

另一个问题是访问创建的矩阵.要访问从0(含1)到3(含3)的行的第0个元素，您需要调用:

The other issue is accessing created matrix. To access 0th elements of rows from 1 inclusive to 3 inclusive you need to call:

mat[1:4,0]=1

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