How to extract values at particular interval ?

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Aarti Soni
Aarti Soni on 16 Oct 2022
Answered: Star Strider on 16 Oct 2022
Hello everyone,
I have a time series matrix (A = 180x360x48) and array (B = 1x48) and I want to extract values at every after 4th interval. In matrix A, the third dimension is time.
Basically, I want to create a new matrix and array which will have only 12 values. e.g., 1,5,9,13,17, 21, 25, 29, 33, 37, 41, 45
Output will be A = 180x360x12, B = 1x12
How can I do this?
Thanks

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Accepted Answer

Star Strider
Star Strider on 16 Oct 2022
Ran in:
Try something like this —
A = randi(9,3,4,48)
A =
A(:,:,1) = 2 2 7 1 8 8 4 7 7 1 9 9 A(:,:,2) = 5 4 8 9 8 9 7 4 6 8 6 3 A(:,:,3) = 5 6 9 2 1 4 1 7 8 8 9 8 A(:,:,4) = 9 5 9 2 2 6 5 9 8 8 7 5 A(:,:,5) = 4 3 9 4 5 7 1 9 3 1 7 9 A(:,:,6) = 6 1 4 7 9 7 6 2 2 6 6 5 A(:,:,7) = 6 5 6 1 1 5 9 6 5 6 8 9 A(:,:,8) = 1 5 2 9 8 6 7 4 8 7 8 9 A(:,:,9) = 9 9 1 9 4 3 4 2 4 2 4 9 A(:,:,10) = 7 4 8 1 6 7 9 1 8 8 6 9 A(:,:,11) = 5 1 2 4 2 8 8 6 3 7 6 5 A(:,:,12) = 1 5 9 9 9 3 6 1 2 2 3 9 A(:,:,13) = 2 9 5 9 7 6 8 2 6 3 8 4 A(:,:,14) = 8 4 1 2 6 2 3 3 6 2 3 9 A(:,:,15) = 6 4 8 5 2 8 2 9 6 2 9 7 A(:,:,16) = 7 4 9 5 3 3 4 9 6 6 6 5 A(:,:,17) = 4 2 6 5 7 9 9 1 5 4 9 6 A(:,:,18) = 5 7 4 5 3 7 7 1 1 7 5 1 A(:,:,19) = 7 7 8 4 2 1 4 6 1 4 9 9 A(:,:,20) = 5 8 1 7 2 4 9 8 3 5 1 6 A(:,:,21) = 9 5 4 9 4 6 5 8 4 7 4 2 A(:,:,22) = 2 3 9 6 3 3 4 4 1 4 9 6 A(:,:,23) = 3 3 6 8 2 1 9 6 9 3 8 9 A(:,:,24) = 1 1 9 4 5 8 7 3 5 7 2 1 A(:,:,25) = 3 6 7 5 1 3 4 9 4 8 3 7 A(:,:,26) = 8 3 8 1 5 7 5 4 9 2 6 7 A(:,:,27) = 7 5 4 1 3 8 9 5 4 5 5 5 A(:,:,28) = 8 1 1 5 4 7 1 6 8 2 1 4 A(:,:,29) = 7 9 8 9 4 7 1 4 4 8 6 3 A(:,:,30) = 8 1 8 9 4 2 1 9 2 8 3 8 A(:,:,31) = 2 6 3 5 7 7 5 8 8 4 5 4 A(:,:,32) = 9 4 1 2 3 8 4 6 6 8 7 8 A(:,:,33) = 1 7 6 6 9 2 3 2 1 8 1 5 A(:,:,34) = 5 9 1 6 3 7 4 6 7 8 6 8 A(:,:,35) = 6 7 8 5 6 2 2 4 1 6 6 3 A(:,:,36) = 8 8 9 5 1 3 4 5 3 3 4 4 A(:,:,37) = 4 5 3 5 1 6 1 2 6 9 1 6 A(:,:,38) = 9 1 5 7 3 9 8 6 9 7 3 2 A(:,:,39) = 2 1 8 3 2 7 6 3 7 1 4 5 A(:,:,40) = 5 3 8 4 8 9 7 9 6 3 2 2 A(:,:,41) = 6 7 6 2 4 4 8 5 2 1 7 1 A(:,:,42) = 7 2 9 6 5 5 3 8 7 3 6 5 A(:,:,43) = 3 5 2 7 5 5 2 7 4 6 8 2 A(:,:,44) = 1 7 4 6 7 1 4 8 3 1 4 7 A(:,:,45) = 5 2 8 7 4 9 8 5 7 3 3 1 A(:,:,46) = 9 2 1 3 2 1 4 6 6 3 6 5 A(:,:,47) = 3 5 1 7 5 3 7 7 5 8 3 1 A(:,:,48) = 5 5 5 9 3 1 6 4 2 1 3 5
B = randi([11 19], 1, 48)
B = 1×48
15 11 15 17 15 19 15 12 12 18 11 16 13 18 18 14 17 18 18 15 19 14 16 12 18 17 17 16 14 18
iv = 1:4:48 % Index Vector
iv = 1×12
1 5 9 13 17 21 25 29 33 37 41 45
Anew = A(:,:,iv)
Anew =
Anew(:,:,1) = 2 2 7 1 8 8 4 7 7 1 9 9 Anew(:,:,2) = 4 3 9 4 5 7 1 9 3 1 7 9 Anew(:,:,3) = 9 9 1 9 4 3 4 2 4 2 4 9 Anew(:,:,4) = 2 9 5 9 7 6 8 2 6 3 8 4 Anew(:,:,5) = 4 2 6 5 7 9 9 1 5 4 9 6 Anew(:,:,6) = 9 5 4 9 4 6 5 8 4 7 4 2 Anew(:,:,7) = 3 6 7 5 1 3 4 9 4 8 3 7 Anew(:,:,8) = 7 9 8 9 4 7 1 4 4 8 6 3 Anew(:,:,9) = 1 7 6 6 9 2 3 2 1 8 1 5 Anew(:,:,10) = 4 5 3 5 1 6 1 2 6 9 1 6 Anew(:,:,11) = 6 7 6 2 4 4 8 5 2 1 7 1 Anew(:,:,12) = 5 2 8 7 4 9 8 5 7 3 3 1
Bnew = B(iv)
Bnew = 1×12
15 15 12 13 17 19 18 14 17 15 19 15
I limited the ‘A’ matrix row and column dimensions to make the result more understandable. I have no idea what are actually in the matriix or vector.
.

More Answers (1)

Torsten
Torsten on 16 Oct 2022
Ran in:
A = rand(180,360,48);
B = [1,5,9,13,17, 21, 25, 29, 33, 37, 41, 45];
A = A(:,:,B);
size(A)
ans = 1×3
180 360 12

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