Produce a new matrix,Z from X and Y matrices

Question

JL 2019-8-8

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/475414-produce-a-new-matrix-z-from-x-and-y-matrices

评论： JL 2019-8-8

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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Answer 1

Star Strider 2019-8-8

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/475414-produce-a-new-matrix-z-from-x-and-y-matrices#answer_386810

在 MATLAB Online 中打开

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:

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