Split matrix into N Equal Parts by rows
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Hi,
I have an Nx10 matrix. How can I split this into three equally sized matrices (by number of rows) ? Is this something the reshape command can handle?
Thank you!
IP
采纳的回答
If N is a multiple of 3, you can download blkReshape,
N=12; M=10;
A=reshape(1:N*M,N,M),
B=blkReshape(A,[N/3,M],1,1,[]),
A =
1 13 25 37 49 61 73 85 97 109
2 14 26 38 50 62 74 86 98 110
3 15 27 39 51 63 75 87 99 111
4 16 28 40 52 64 76 88 100 112
5 17 29 41 53 65 77 89 101 113
6 18 30 42 54 66 78 90 102 114
7 19 31 43 55 67 79 91 103 115
8 20 32 44 56 68 80 92 104 116
9 21 33 45 57 69 81 93 105 117
10 22 34 46 58 70 82 94 106 118
11 23 35 47 59 71 83 95 107 119
12 24 36 48 60 72 84 96 108 120
B(:,:,1) =
1 13 25 37 49 61 73 85 97 109
2 14 26 38 50 62 74 86 98 110
3 15 27 39 51 63 75 87 99 111
4 16 28 40 52 64 76 88 100 112
B(:,:,2) =
5 17 29 41 53 65 77 89 101 113
6 18 30 42 54 66 78 90 102 114
7 19 31 43 55 67 79 91 103 115
8 20 32 44 56 68 80 92 104 116
B(:,:,3) =
9 21 33 45 57 69 81 93 105 117
10 22 34 46 58 70 82 94 106 118
11 23 35 47 59 71 83 95 107 119
12 24 36 48 60 72 84 96 108 120
2 个评论
Inna Pelloso
2022-9-3
编辑：Inna Pelloso
2022-9-3
Matt J
2022-9-3
You can pad with additional rows, e.g.,
N=ceil(N/3)*3;
A(end+1:N,:)=nan;
更多回答（2 个）
Walter Roberson
2022-9-4
pieces = 3;
N = size(A, 1);
part_sizes = floor(N/pieces) * [1 1];
part_sizes(end+1) = N - sum(part_sizes);
C = mat2cell(A, part_sizes, size(A,2));
C is now a cell array in which the rows are equally divided as possible, with the last block being shorter if necessary.
2 个评论
Gorkem
2024-3-5
Thanks for the code. I was having trouble with the last block being too small compared to other blocks so I distributed residuals of the last block through the equally spaced blocks. It's not the best but here is the version I updated in this way:
pieces = 100;
N = size(A, 1);
part_sizes = floor(N/pieces) * [ones(1:pieces)];
Res = N - sum(part_sizes);
part_sizes(1:Res) = part_sizes(1:Res) + 1;
C = mat2cell(A, part_sizes, size(A,2));
AlexDiz
2024-8-16
it's [ones(1, pieces)] instead of [ones(1:pieces)]
but it works perfectly !
thanks
You can also use mat2tiles,
which doesn't require even multiples of the block size. However, it is never advisable to use cell arrays when you don't have to.
A=rand(14,6);
B=mat2tiles(A,[4,inf]) %group every 4 rows
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