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For loop to create a matrix array

조회 수: 114 (최근 30일)
Cutie
Cutie 2022년 2월 6일
댓글: Image Analyst 2023년 2월 21일
I have a data X say
X= 1:100 (integer 1 to 100)
I want to write a for loop that will create matrix of w=10x5 (10rows, 5 columns) where by column 1 will be the first 10 elements of X (1 to 10), column 2 (11 to 20) and so on and then stop at column 5 (41 to 50) before creating another matrix say w2 (ie starting the iteration again).
I don't want to use reshape function as it won't fit into the real data I am working on.
  댓글 수: 4
Image Analyst
Image Analyst 2022년 2월 6일
편집: Image Analyst 2022년 2월 6일
For 90, what are the sizes of the two matrices?
  1. 9-by-5? (in which case, my answer below works)
  2. Or one matrix of 10-by-5 and the second one of 10-by-4?
Cutie
Cutie 2022년 2월 7일
I appreciate @Matt J and @Image Analyst for offering your help.

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채택된 답변

Matt J
Matt J 2022년 2월 6일
편집: Matt J 2022년 2월 6일
Because, I may need to create matrix of size 9 by 5. In which case I will only have 2 matrices formed from the first 90 elements (1:90) and the last 10 element can be discarded.
That doesn't disqualify reshape.
rows=9;
cols=5;
X=1:100;
M=rows*cols;
N=numel(X);
X=reshape( X(1:floor(N/M)*M) ,rows,cols,[]);
w=squeeze(num2cell(X,[1,2]))
w = 2×1 cell array
{9×5 double} {9×5 double}
  댓글 수: 1
Cutie
Cutie 2022년 2월 7일
Thank you very much @Matt J. This works and it opens my eyes to other things.

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추가 답변 (1개)

Image Analyst
Image Analyst 2022년 2월 6일
편집: Image Analyst 2022년 2월 6일
Try this
N = 100; % or 90 or some other multiple of 10
X= 1 : N; % (integer 1 to 100)
x1 = reshape(X(1:N/2)', N/10, [])
x1 = 10×5
1 11 21 31 41 2 12 22 32 42 3 13 23 33 43 4 14 24 34 44 5 15 25 35 45 6 16 26 36 46 7 17 27 37 47 8 18 28 38 48 9 19 29 39 49 10 20 30 40 50
x2 = reshape(X(N/2+1:end), N/10, [])
x2 = 10×5
51 61 71 81 91 52 62 72 82 92 53 63 73 83 93 54 64 74 84 94 55 65 75 85 95 56 66 76 86 96 57 67 77 87 97 58 68 78 88 98 59 69 79 89 99 60 70 80 90 100
If you don't want to use reshape for some weird reason, you can do it with a for loop but it will be more complicated.
X = 1 : 100;
x3 = zeros(10, 5);
x4 = zeros(10, 5);
k = 1;
for col = 1 : 5
for row = 1 : 10
x3(row, col) = X(k);
x4(row, col) = X(k + 50);
k = k + 1;
end
end
x3
x3 = 10×5
1 11 21 31 41 2 12 22 32 42 3 13 23 33 43 4 14 24 34 44 5 15 25 35 45 6 16 26 36 46 7 17 27 37 47 8 18 28 38 48 9 19 29 39 49 10 20 30 40 50
x4
x4 = 10×5
51 61 71 81 91 52 62 72 82 92 53 63 73 83 93 54 64 74 84 94 55 65 75 85 95 56 66 76 86 96 57 67 77 87 97 58 68 78 88 98 59 69 79 89 99 60 70 80 90 100
  댓글 수: 3
Navita
Navita 2023년 2월 21일
Output not showing
Image Analyst
Image Analyst 2023년 2월 21일
@Navita as you can see above there is an output. I ran it in the editor with the green run triangle and there is definitely an output. Just look at my Answer and you can see it.
If you don't have any output then you must have copied my code and changed it somehow.
If you have any more questions, then attach your data and code to read it in with the paperclip icon after you read this:

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