Could anyone help me how to extract different specific number of rows in a matrix.

I am a matrix of size A= rand(100,1)

I want to generate matrix by extracting 2 rows in interval of 5.

B=A([1:2,6:7,11:12,16:17,........,96:97],:).

Could anyone help me to write in the simplified form to execute in matlab.

Answer 1

[Walter Roberson]

row_idx = reshape((1:5:100) + [0;1],1,[])

row_idx = 1×40

1 2 6 7 11 12 16 17 21 22 26 27 31 32 36 37 41 42 46 47 51 52 56 57 61 62 66 67 71 72

[jaah navi]

ok. In addition i want to extract the values of the row_idx in a separate matrix. Could you help me on this.

[Walter Roberson]

?? row_idx is already a separate matrix. You take it and

B = A(row_idx,:);

[Walter Roberson]

For 2, 3, 4 of each group of 5,

row_idx = reshape((1:5:100) + [1;2;3],1,[])

Answer 2

[Scott MacKenzie]

B = A(sort([1:5:100 2:5:100]))

[jaah navi]

Thanks for your help.

[jaah navi]

If suppose instead of two rows I need to have value of 2,3,4 in each intervals of 5. In that case the above command doesnt executes. could you help me on this.