How to find compare unequal size matrices and create new matrix by combining them??

Question

Iro 2013-5-6

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Hi, I have the following matrices:

X = [1001 1011 1001 10 130 0.8 0.2;
1012 1001 11 150 0.2 0.8;
1012 1001 11 131 0.5 0.5;
1012 1002 11 140 0.6 0.4];
Y = [1001 1011 1001 10 112 1 122 214;
1011 1001 11 221 1 134 113; % extra row
1012 1001 11 98 1 58 82;
1012 1001 11 68 1 59 67;
1012 1002 11 32 1 56 98;
1012 1005 12 67 1 89 132]; % extra row

and I want to get this :

M = [1001 1011 1001 10 130 0.8 0.2;
1011 1001 11 NaN NaN NaN; % or sth equivalent to NaN
1012 1001 11 150 0.2 0.8;
1012 1001 11 131 0.5 0.5;
1012 1002 11 140 0.6 0.4;
1012 1005 12 NaN NaN NaN];

I have difficulty in finding/comparing 4 elements together of every row (M(:,1:4)), and also when the size of the matrices in not equal...

Any suggestions on which could be the right function to solve it??

Thanks,

Iro

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Sean de Wolski 2013-5-7

I'm not clear on how you derived M. Can you be very specific, where does each row in M come from?

Iro 2013-5-7

M is the result I want to get with some function, derived from X an Y. More specifically, the four first columns come from Y's first 4 columsn while the rest 3 columns come from X's last three columns, in the case where the combinations of the first 4 column of Y are the same with combinations of X's first 4 columns... e.g: if M(i,1:4) is the same to any of X(j,1:4), then assign elements of X(j,5:7) to the M(i,5:end) by discarding the existing ones..

Let me know if it makes more sense now...Thanks!! :)

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Answer 1

Andrei Bobrov 2013-5-7

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https://ww2.mathworks.cn/matlabcentral/answers/74810-how-to-find-compare-unequal-size-matrices-and-create-new-matrix-by-combining-them#answer_84670

在 MATLAB Online 中打开

ii = ismember(Y(:,1:4),X(:,1:4),'rows');
M = [Y(:,1:4),nan(size(Y,1),3)];
M(ii,5:end) = X(:,5:end);

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Iro 2013-5-9

编辑：Iro 2013-5-9

在 MATLAB Online 中打开

and what about when I have multiple rows with the same (r,1:4) combinations in Y? For example:

X = [1001 1011 1001 10 130 0.8 0.2;
1012 1001 11 150 0.2 0.8;
1012 1002 11 131 0.5 0.5;
1013 1002 11 140 0.6 0.4];
Y = [1001 1011 1001 10 112 1 122 214;
1011 1001 11 221 1 134 113; % extra (r,1:4) combination
1011 1001 11 221 1 115 112; % extra multiple comb
1012 1001 11 98 1 58 82; % multiple existing comb
1012 1001 11 98 1 35 72; % multiple existing comb
1012 1001 11 98 1 68 62; % multiple existing comb
1012 1002 11 68 1 59 67;
1013 1002 11 32 1 56 98;
1012 1005 12 67 1 89 132]; % extra comb

I tried with

[tf,loc] = ismember(Y(:,1:4),X(:,1:4),'rows')
M = [Y(:,1:4),nan(size(Y,1),3)];
M(tf,5:end) = X(loc,5:end);

in order to get this:

    M = [1001 1011 1001 10 130 0.8 0.2; % taken from X(1,5:end)
        1001 1011 1001 11 nan nan nan; 
        1001 1011 1001 11 nan nan nan; 
        1001 1012 1001 11 150 0.2 0.8; % taken from X(2,5:end)
        1001 1012 1001 11 150 0.2 0.8; % taken from X(2,5:end)
        1001 1012 1001 11 150 0.2 0.8; % taken from X(2,5:end)
        1001 1012 1002 11 131 0.5 0.5; % taken from X(3,5:end)
        1001 1013 1002 11 140 0.6 0.4; % taken from X(4,5:end)
        1004 1012 1005 12 nan nan nan]; %

but I get the error:

??? Subscript indices must either be real positive integers or logicals.

in the last line of my code.

Iro 2013-5-9

编辑：Iro 2013-5-9

在 MATLAB Online 中打开

Well I tried it with:

M(tf,5:end) = X(loc(tf),5:end);

instead, and it seems to work. However I don't really understand what is the difference between loc and loc(tf) in relation to the error above (real positive integer or logical)... any hints?