How to transform a matrix to a binary type in Matlab?

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Moe 2016-2-25

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评论： Moe 2016-2-29

Matrix A is as follows:

A = [0  240  245  250
25  1  2  1
63  3  2  1];

First row is header of the matrix.

Except column1 that is unique id, there are 3 different variables in the matrix. I want matrix A transformed to the binary matrix, like the following matrix:

    B = [
  0,240,240,250
    25,1,0,1
    25,0,1,0
    25,0,0,0
    63,0,0,1
    63,0,1,0
    63,1,0,0];

Id 25 and 63 repeated 3 times, because there are 3 types of variables. For example, first row: 1,0,1 represents that there was type 1 in the matrix A(2,2) and no type 1 in A(2,3) and 1 in A(2,4).

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James Tursa 2016-2-25

In your example, the "25" rows are ordered by the types 1, 2, 3. But in the "63" rows, they are ordered by the types 3, 2, 1. Is this how you really want it? I.e., you don't want it always ordered by 1, 2,3, but you want the output ordered by how the arrangement is in A?

Moe 2016-2-25

Thanks James,

I want it always ordered by 1, 2,3.

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Answer 1

James Tursa 2016-2-25

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https://ww2.mathworks.cn/matlabcentral/answers/269885-how-to-transform-a-matrix-to-a-binary-type-in-matlab#answer_211131

编辑：James Tursa 2016-2-25

在 MATLAB Online 中打开

E.g., using a loop:

[m,n] = size(A);
n1 = n - 1;
B = zeros((m-1)*n1+1,n);
B(1,:) = A(1,:);
for k=2:m
    kx = (k-2)*n1 + 2;
    B(kx:kx+n1-1,1) = A(k,1);
    B(kx:kx+n1-1,2:n) = bsxfun(@eq,(1:n1)',A(k,2:n));
end

A little bit harder to follow, but without the loop:

[m,n] = size(A);
n1 = n - 1;
Adata = A(2:m,2:n);
Bcol1 = ones(n1,1)*A(2:m,1)';
Bdata = reshape(bsxfun(@eq,(1:n1)',Adata(:)'),[],n1);
B = [A(1,:); Bcol1(:) Bdata];

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Image Analyst 2016-2-27

I'm curious why you need this strange array. What do you want to do once you have it? There may be a more straightforward or simpler way of accomplishing that.

Moe 2016-2-29