Produce a new matrix,Z from X and Y matrices
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I have 2 matrices, and I would like to derive another matrix, Z from X and Y. So for each row starting and ending the same, sum of their corresponding values in X. For example, in Y, any row starting and ending with 1 and 2 respectively, loop up at their X values, and sum them up i.e. 25+1+3=29. Then perform the same method for the rest.
X = [25;
1;
3;
28;
6;
7;
25;
6;
9;
25;
10;
11;
15;
14;
12;
13;
25;
14;
15;]
Y = [1 2 0 0;
1 3 2 0;
1 4 3 2;
1 3 0 0;
1 2 3 0;
1 4 3 0;
1 4 0 0;
1 3 4 0;
1 2 3 4;
2 3 0 0;
2 1 3 0;
2 1 4 3;
2 1 4 0;
2 3 4 0;
2 1 3 4;
2 3 1 4;
3 4 0 0;
3 1 4 0;
3 2 1 4;]
Z = [25+1+3; % start ‘1’ and end with ‘2’
28+6+7; % start ‘1’ and end with ‘3’
25+6+9; % start ‘1’ and end with ‘4’
25+10+11; % start ‘2’ and end with ‘3’
15+14+12+13; % start ‘2’ and end with ‘4’
25+14+15;] % start ‘3’ and end with ‘4’
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Accepted Answer
Star Strider
on 8 Aug 2019
One option:
for k = 1:size(Y,1)
[~,Zc] = find(Y(k,:) ~= 0, 1, 'last'); % Last Non-Zero Column
Z2(k,:) = Y(k,Zc); % Element Of Last Non-Zero Column
end
Z = accumarray([Z2 Y(:,1)], X)
producing:
Z =
0 0 0
29 0 0
41 46 0
40 54 54
To print it out:
[Zs,Ze] = meshgrid(1:3, 1:4);
Zsc = Zs(:);
Zec = Ze(:);
fprintf(1, 'Starts with %d, Ends with %d, Z = %2d\n', [Zs(:), Ze(:), Z(:)]')
producing:
Starts with 1, Ends with 1, Z = 0
Starts with 1, Ends with 2, Z = 29
Starts with 1, Ends with 3, Z = 41
Starts with 1, Ends with 4, Z = 40
Starts with 2, Ends with 1, Z = 0
Starts with 2, Ends with 2, Z = 0
Starts with 2, Ends with 3, Z = 46
Starts with 2, Ends with 4, Z = 54
Starts with 3, Ends with 1, Z = 0
Starts with 3, Ends with 2, Z = 0
Starts with 3, Ends with 3, Z = 0
Starts with 3, Ends with 4, Z = 54
Experiment to get the result you want.
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