Matrix line by line

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TheDice 2021-4-20

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/807282-matrix-line-by-line

评论： TheDice 2021-4-20

采纳的回答： Walter Roberson

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how can i go through a matrix line by line?

I have this matrix and would like to have the value of a spinner depending on the value.

x = [1:1:5; 6:1:10]

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Answer 1

Walter Roberson 2021-4-20

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https://ww2.mathworks.cn/matlabcentral/answers/807282-matrix-line-by-line#answer_679647

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x = [1:1:5; 6:1:10; 11:15; 16:20; 21:25; 26:30; 31:35; [36, 0, -1, nan, nan]];
nrow = size(x,1);
for K = 1 : 5
   spin = randi(nrow);
   randrow = x(spin,:)
end
randrow = 1×5
    11    12    13    14    15
randrow = 1×5
    26    27    28    29    30
randrow = 1×5
    26    27    28    29    30
randrow = 1×5
    11    12    13    14    15
randrow = 1×5
    31    32    33    34    35

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Walter Roberson 2021-4-20

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It sounds like you want linear indexing, but row by row

x = [1:1:5; 6:1:10; 11:15; 16:20; 21:25; 26:30; 31:35; [36, 0, -1, nan, nan]];
nent = numel(x);
xt = x.';
for K = 1 : 5
   spin = randi(nent);
   randval = xt(spin);
   [spin, randval]
end
ans = 1×2
     1     1
ans = 1×2
    37     0
ans = 1×2
    19    19
ans = 1×2
    35    35
ans = 1×2
    30    30

The entries in the array happen to all be equal to their index when operating with that scheme, except for the last few, and you can see in my example that indeed it happened to pull out the stored value (0) at index 37

TheDice 2021-4-20