How do I code for this random situation?

Question

NAA 2023-3-20

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1931610-how-do-i-code-for-this-random-situation

评论： Image Analyst 2023-3-20

采纳的回答： Image Analyst

On a r*c size grid, 55% of the sites are randomly filled with X, 2% randomly filled with Y, and the rest are empty

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NAA 2023-3-20

There was no previous question like this, and I saw your comment on the other question, you didn't answer. Instead you just left a rude comment like the one here

Image Analyst 2023-3-20

在 MATLAB Online 中打开

@NAA, OK try it this way:

r = 10;
c = 20;
output = nan(r, c);
numX = round(0.55 * r * c) % Number of elements to place an X into.
numY = round(0.02 * r * c) % Number of elements to place a Y into.
X = 1;
Y = 2;
output(1 : numX) = X;
output(numX + 1 : numX + numY) = Y;
randomIndexes = randperm(numel(output));
output = reshape(output(randomIndexes), [r, c])

There are other ways that would work also.

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Answer 1

Image Analyst 2023-3-20

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1931610-how-do-i-code-for-this-random-situation#answer_1196355

在 MATLAB Online 中打开

This looks like a homework problem. If you have any questions ask your instructor or read the link below to get started:

How do I get help on homework questions on MATLAB Answers? - MATLAB Answers - MATLAB Central

Obviously we can't give you the full solution because you're not allowed to turn in our code as your own.

Hint:

output = nan(r, c);
numX = round(0.55 * r * c); % Number of elements to place an X into.
numY = round(0.02 * r * c); % Number of elements to place a Y into.

Two ways to do it:

You can do it vectorized using randperm (assign the X to the first numX elements, then assign Y to the next numY elements, then use randperm to scramble the order), or
you can do it brute force using a for loop to place the x value and another loop to place the Y value, but only in the location if the value is a nan (not an X).