How to get certain matrix columns.

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

Answer 1

[Stephan]

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

[Santos García Rosado]

Thank you!