How to create the matrix AxB in Python?

Question

I am trying to create this matrix AxB with a specific pattern in Python :

[1.0, 0.0, 0.0],
[-1.0, 0.0, 0.0],
[0.0, 1.0, 0.0],
[0.0, -1.0, 0.0],
[0.0, 0.0, 1.0],
[0.0, 0.0, -1.0]

The problem is that I want to create this matrix without having to resort to hard coding it. Can someone help me to isolate the pattern, and fill the matrix dynamically?

Here is what I've tried so far :

matrix_test = [[0.0 for i in range(3)] for i in range(6)]
for x in range(3):
    matrix_test [x][x] = 1.0

http://stackoverflow.com/questions/6667201/how-to-define-two-dimensional-array-in-python — Vadim Pushtaev, May 13 '16 at 13:48
I need the 2 first rows is [1.0, 0.0, 0.0], [-1.0, 0.0, 0.0], And the next is [0.0, 1.0, 0.0], [0.0, -1.0, 0.0], and next ... — Hien Bui, May 13 '16 at 13:51
This is not a duplicate. What OP wants is not just how to make a list-of-lists to represent a matrix, but a matrix with a certain pattern in it. — drdaeman, May 13 '16 at 14:06
@HienBui: the question was closed but here you go: https://gist.github.com/drdaeman/f88ce23a013389e0118f86e91a44f97c — drdaeman, May 13 '16 at 14:07
@drdaeman: thank you so much for your helping and your explanation — Hien Bui, May 13 '16 at 14:10

Nils Werner · Accepted Answer · 2016-05-13T14:03:30.240

2

matrix_test = [[0.0 for i in range(3)] for i in range(6)]
for x in range(3):
    matrix_test [2 * x][x] = 1.0
    matrix_test [2 * x + 1][x] = -1.0

edited May 13 '16 at 14:03

answered May 13 '16 at 13:57

Nils Werner

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Thank you so much for your help. I think this solution doesn't correct. I have tried with this also and get the result: [1.0, 0.0, 0.0], [-1.0, 1.0, 0.0], [0.0, -1.0, 1.0], [0.0, 0.0, -1.0], [0.0, 0.0, 0.0], [0.0, 0.0, 0.0] – Hien Bui May 13 '16 at 14:01
Use `2*x` and `2*x+1` for the first index instead of `x` and `x+1`. – xnx May 13 '16 at 14:02
thanks for the hint, @Hien Bui try again – Nils Werner May 13 '16 at 14:04
Thank you Nils Werner and xnx for your helping. – Hien Bui May 13 '16 at 14:15

How to create the matrix AxB in Python?

1 Answers1