How to convert row-major linear indices to column-major indices?

Question

Preetham Manjunatha 2022-3-23

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https://ww2.mathworks.cn/matlabcentral/answers/1678339-how-to-convert-row-major-linear-indices-to-column-major-indices

评论： Preetham Manjunatha 2022-3-24

I have a row-major linear indices [1,8, 14, 9, 4, 11, 18] from a matrix 3 x 6 (row x column). How to convert this to column-major linear indices [1, 5, 6, 8, 10, 14, 18] without for-loops? I want to generalize for any rectangular or square matrices.

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Answer 1

Stephen23 2022-3-23

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https://ww2.mathworks.cn/matlabcentral/answers/1678339-how-to-convert-row-major-linear-indices-to-column-major-indices#answer_924829

编辑：Stephen23 2022-3-23

在 MATLAB Online 中打开

S = [3,6]; % matrix size
X = [1,8,14,9,4,11,18]; % row-major linear indices
[Y,Z] = ind2sub(flip(S),X);
V = sub2ind(S,Z,Y) % column-major linear indices
V = 1×7
     1     5     6     8    10    14    18

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Stephen23 2022-3-24

在 MATLAB Online 中打开

S = [3,6]; % matrix size
X = [1,5,6,8,10,14,18]; % column-major linear indices
[Y,Z] = ind2sub(S,X);
V = sub2ind(flip(S),Z,Y) % row-major linear indices
V = 1×7
     1     8    14     9     4    11    18

Preetham Manjunatha 2022-3-24

Thanks!

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Answer 2

Arif Hoq 2022-3-23

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https://ww2.mathworks.cn/matlabcentral/answers/1678339-how-to-convert-row-major-linear-indices-to-column-major-indices#answer_924804

编辑：Arif Hoq 2022-3-23

在 MATLAB Online 中打开

try reshape function:

A=[1 2 3 4 5 6; 7 8 9 10 11 12;13 14 15 16 17 18]  % any matrix
A = 3×6
     1     2     3     4     5     6
     7     8     9    10    11    12
    13    14    15    16    17    18
D=reshape(A,[],3)
D = 6×3
     1     3     5
     7     9    11
    13    15    17
     2     4     6
     8    10    12
    14    16    18