How to get certain matrix columns.

Question

Santos García Rosado 2021-4-21

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/808840-how-to-get-certain-matrix-columns

评论： Santos García Rosado 2021-4-21

采纳的回答： Stephan

在 MATLAB Online 中打开

Hello,

I'm having trouble trying to get certain matrix columns. Let's say I have Matrix A:

A = [1 2 3 4 5 6 7 8 9 10 11 12; 13 14 15 16 17 18 19 20 21 22 23 24]

Let's say I'd like to get every third value starting in position 1. Then I would use this code:

A(:,1:3:end)

My issue is that I'd like to skip four positions and get the next two. This would be my output if I started from the first position:

Output = [1 2 7 8; 13 14 19 20]

I could get every column manually but since I'm working with big matrixes and different sizes it woldn't be convininient.

Can someone come around a solution for this?

Thnak you in advance,

Santos

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Answer 1

Stephan 2021-4-21

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/808840-how-to-get-certain-matrix-columns#answer_680810

编辑：Stephan 2021-4-21

在 MATLAB Online 中打开

A = [1 2 3 4 5 6 7 8 9 10 11 12; 13 14 15 16 17 18 19 20 21 22 23 24]
A = 2×12
     1     2     3     4     5     6     7     8     9    10    11    12
    13    14    15    16    17    18    19    20    21    22    23    24
A1 = reshape(A',2,[])
A1 = 2×12
     1     3     5     7     9    11    13    15    17    19    21    23
     2     4     6     8    10    12    14    16    18    20    22    24
b = A1(:,1:3:end)
b = 2×4
     1     7    13    19
     2     8    14    20
b = b(:)'
b = 1×8
     1     2     7     8    13    14    19    20