Randomly change the location of 1s on a matrix of 0s (randperm on a matrix}

Question

Doobie 2017-4-29

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回答： Image Analyst 2017-4-29

How does one generate a random matrix that satisfies certain properties? Specifically, I'm looking for a code that does this:

Given the matrix below, I want to randomly change the locations of 1s.

So examples would be

0 0      0 0 0      0 0 1
1 0      0 0 0      0 0 0
0 0      0 1 0      1 0 0
0 0      1 0 0      0 0 0

Well the initial matrix is easy enough.

A = zeros(4,3);
A(1:2,1) = ones(2,1);

But I don't know how to proceed from here. randperm() only generates a vector so doesn't work here. Is there a matlab function that does what randperm does on a matrix?

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Answer 1

Image Analyst 2017-4-29

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https://ww2.mathworks.cn/matlabcentral/answers/337927-randomly-change-the-location-of-1s-on-a-matrix-of-0s-randperm-on-a-matrix#answer_265020

在 MATLAB Online 中打开

Here's one way:

m=[...
1 0 0 
1 0 0
0 0 0
0 0 0]
[rows, columns] = size(m);
ne = numel(m)
numOnes = sum(m(:))
% Generate 10 new versions with 1's in different locations each time.
for k = 1 : 10
  m2 = zeros(size(m)); % Initialize
  m2(randperm(ne, numOnes)) = 1;
  % Turn from vector into 2-D matrix
  m2 = reshape(m2, rows, columns)
end

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Answer 2

Star Strider 2017-4-29

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/337927-randomly-change-the-location-of-1s-on-a-matrix-of-0s-randperm-on-a-matrix#answer_265016

See How to place a number in a random position in a matrix of zeros? (link) for one approach. You can create more random 1 values by having the randi function return a vector rather than a single value. See the documentation for the randi function for details.