{"group":{"id":1,"name":"Community","lockable":false,"created_at":"2012-01-18T18:02:15.000Z","updated_at":"2026-06-05T00:10:21.000Z","description":"Problems submitted by members of the MATLAB Central community.","is_default":true,"created_by":161519,"badge_id":null,"featured":false,"trending":false,"solution_count_in_trending_period":0,"trending_last_calculated":"2026-06-05T00:00:00.000Z","image_id":null,"published":true,"community_created":false,"status_id":2,"is_default_group_for_player":false,"deleted_by":null,"deleted_at":null,"restored_by":null,"restored_at":null,"description_opc":null,"description_html":null,"published_at":null},"problems":[{"id":42503,"title":"Generating random matrix with given probability mass function","description":"Inspired by \u003chttp://www.mathworks.com/matlabcentral/cody/problems/2356-simulating-the-selection-of-a-state-with-given-probabilities Problem 2356. Simulating the selection of a state with given probabilities\u003e, let's consider a similar yet more useful problem. Write a function\r\n\r\n                             x = rndsampling(m,n,prob)\r\n\r\nto generate an m-by-n matrix x, whose entries are drawn independently from integer symbols 1:numel(prob) according to the given probability mass function prob. Specifically, symbol k occurs with probability prob(k), k = 1, 2, ..., numel(prob), where all(prob\u003e0) == 1 and sum(prob) == 1.","description_html":"\u003cp\u003eInspired by \u003ca href = \"http://www.mathworks.com/matlabcentral/cody/problems/2356-simulating-the-selection-of-a-state-with-given-probabilities\"\u003eProblem 2356. Simulating the selection of a state with given probabilities\u003c/a\u003e, let's consider a similar yet more useful problem. Write a function\u003c/p\u003e\u003cpre\u003e                             x = rndsampling(m,n,prob)\u003c/pre\u003e\u003cp\u003eto generate an m-by-n matrix x, whose entries are drawn independently from integer symbols 1:numel(prob) according to the given probability mass function prob. Specifically, symbol k occurs with probability prob(k), k = 1, 2, ..., numel(prob), where all(prob\u0026gt;0) == 1 and sum(prob) == 1.\u003c/p\u003e","function_template":"function x = rndsampling(m,n,prob);\r\n  x = rand(m,n)\r\nend","test_suite":"%%\r\nrnd = sort(rand(randi([10,20]),1));\r\nprob = vertcat(rnd(1,:),diff(rnd,1,1),1-rnd(end,:));\r\nsz = [1 1e5;1e5 1;1e3 1e2;randi([100 200], 100, 2)];\r\nsz = sz(randi(size(sz,1)),:);\r\nx = rndsampling(sz(1),sz(2),prob);\r\nprob_est = histcounts(x,1:numel(prob)+1,'Normalization','probability').';\r\nerr = mean(abs(prob_est - prob))\r\nassert(err \u003c 0.005 \u0026\u0026 isequal(size(x),sz) \u0026\u0026 all(~isnan(x(:))));\r\n","published":true,"deleted":false,"likes_count":2,"comments_count":1,"created_by":12569,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":132,"test_suite_updated_at":"2015-08-13T18:44:59.000Z","rescore_all_solutions":false,"group_id":1,"created_at":"2015-08-11T19:26:49.000Z","updated_at":"2026-05-14T19:22:17.000Z","published_at":"2015-08-11T19:26:49.000Z","restored_at":null,"restored_by":null,"spam":false,"simulink":false,"admin_reviewed":false,"description_opc":"{\"relationships\":[{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/document\",\"targetMode\":\"\",\"relationshipId\":\"rId1\",\"target\":\"/matlab/document.xml\"},{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/output\",\"targetMode\":\"\",\"relationshipId\":\"rId2\",\"target\":\"/matlab/output.xml\"}],\"parts\":[{\"partUri\":\"/matlab/document.xml\",\"relationship\":[],\"contentType\":\"application/vnd.mathworks.matlab.code.document+xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\"?\u003e\\n\u003cw:document xmlns:w=\\\"http://schemas.openxmlformats.org/wordprocessingml/2006/main\\\"\u003e\u003cw:body\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eInspired by\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e \u003c/w:t\u003e\u003c/w:r\u003e\u003cw:hyperlink w:docLocation=\\\"http://www.mathworks.com/matlabcentral/cody/problems/2356-simulating-the-selection-of-a-state-with-given-probabilities\\\"\u003e\u003cw:r\u003e\u003cw:t\u003eProblem 2356. Simulating the selection of a state with given probabilities\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:hyperlink\u003e\u003cw:r\u003e\u003cw:t\u003e, let's consider a similar yet more useful problem. Write a function\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"code\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003e\u003c![CDATA[                             x = rndsampling(m,n,prob)]]\u003e\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eto generate an m-by-n matrix x, whose entries are drawn independently from integer symbols 1:numel(prob) according to the given probability mass function prob. Specifically, symbol k occurs with probability prob(k), k = 1, 2, ..., numel(prob), where all(prob\u0026gt;0) == 1 and sum(prob) == 1.\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003c/w:body\u003e\u003c/w:document\u003e\"},{\"partUri\":\"/matlab/output.xml\",\"contentType\":\"text/xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\" standalone=\\\"no\\\" ?\u003e\u003cembeddedOutputs\u003e\u003cmetaData\u003e\u003cevaluationState\u003emanual\u003c/evaluationState\u003e\u003clayoutState\u003ecode\u003c/layoutState\u003e\u003coutputStatus\u003eready\u003c/outputStatus\u003e\u003c/metaData\u003e\u003coutputArray type=\\\"array\\\"/\u003e\u003cregionArray type=\\\"array\\\"/\u003e\u003c/embeddedOutputs\u003e\"}]}"}],"problem_search":{"problems":[{"id":42503,"title":"Generating random matrix with given probability mass function","description":"Inspired by \u003chttp://www.mathworks.com/matlabcentral/cody/problems/2356-simulating-the-selection-of-a-state-with-given-probabilities Problem 2356. Simulating the selection of a state with given probabilities\u003e, let's consider a similar yet more useful problem. Write a function\r\n\r\n                             x = rndsampling(m,n,prob)\r\n\r\nto generate an m-by-n matrix x, whose entries are drawn independently from integer symbols 1:numel(prob) according to the given probability mass function prob. Specifically, symbol k occurs with probability prob(k), k = 1, 2, ..., numel(prob), where all(prob\u003e0) == 1 and sum(prob) == 1.","description_html":"\u003cp\u003eInspired by \u003ca href = \"http://www.mathworks.com/matlabcentral/cody/problems/2356-simulating-the-selection-of-a-state-with-given-probabilities\"\u003eProblem 2356. Simulating the selection of a state with given probabilities\u003c/a\u003e, let's consider a similar yet more useful problem. Write a function\u003c/p\u003e\u003cpre\u003e                             x = rndsampling(m,n,prob)\u003c/pre\u003e\u003cp\u003eto generate an m-by-n matrix x, whose entries are drawn independently from integer symbols 1:numel(prob) according to the given probability mass function prob. Specifically, symbol k occurs with probability prob(k), k = 1, 2, ..., numel(prob), where all(prob\u0026gt;0) == 1 and sum(prob) == 1.\u003c/p\u003e","function_template":"function x = rndsampling(m,n,prob);\r\n  x = rand(m,n)\r\nend","test_suite":"%%\r\nrnd = sort(rand(randi([10,20]),1));\r\nprob = vertcat(rnd(1,:),diff(rnd,1,1),1-rnd(end,:));\r\nsz = [1 1e5;1e5 1;1e3 1e2;randi([100 200], 100, 2)];\r\nsz = sz(randi(size(sz,1)),:);\r\nx = rndsampling(sz(1),sz(2),prob);\r\nprob_est = histcounts(x,1:numel(prob)+1,'Normalization','probability').';\r\nerr = mean(abs(prob_est - prob))\r\nassert(err \u003c 0.005 \u0026\u0026 isequal(size(x),sz) \u0026\u0026 all(~isnan(x(:))));\r\n","published":true,"deleted":false,"likes_count":2,"comments_count":1,"created_by":12569,"edited_by":null,"edited_at":null,"deleted_by":null,"deleted_at":null,"solvers_count":132,"test_suite_updated_at":"2015-08-13T18:44:59.000Z","rescore_all_solutions":false,"group_id":1,"created_at":"2015-08-11T19:26:49.000Z","updated_at":"2026-05-14T19:22:17.000Z","published_at":"2015-08-11T19:26:49.000Z","restored_at":null,"restored_by":null,"spam":false,"simulink":false,"admin_reviewed":false,"description_opc":"{\"relationships\":[{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/document\",\"targetMode\":\"\",\"relationshipId\":\"rId1\",\"target\":\"/matlab/document.xml\"},{\"relationshipType\":\"http://schemas.mathworks.com/matlab/code/2013/relationships/output\",\"targetMode\":\"\",\"relationshipId\":\"rId2\",\"target\":\"/matlab/output.xml\"}],\"parts\":[{\"partUri\":\"/matlab/document.xml\",\"relationship\":[],\"contentType\":\"application/vnd.mathworks.matlab.code.document+xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\"?\u003e\\n\u003cw:document xmlns:w=\\\"http://schemas.openxmlformats.org/wordprocessingml/2006/main\\\"\u003e\u003cw:body\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eInspired by\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e \u003c/w:t\u003e\u003c/w:r\u003e\u003cw:hyperlink w:docLocation=\\\"http://www.mathworks.com/matlabcentral/cody/problems/2356-simulating-the-selection-of-a-state-with-given-probabilities\\\"\u003e\u003cw:r\u003e\u003cw:t\u003eProblem 2356. Simulating the selection of a state with given probabilities\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:hyperlink\u003e\u003cw:r\u003e\u003cw:t\u003e, let's consider a similar yet more useful problem. Write a function\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"code\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003e\u003c![CDATA[                             x = rndsampling(m,n,prob)]]\u003e\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"text\\\"/\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eto generate an m-by-n matrix x, whose entries are drawn independently from integer symbols 1:numel(prob) according to the given probability mass function prob. Specifically, symbol k occurs with probability prob(k), k = 1, 2, ..., numel(prob), where all(prob\u0026gt;0) == 1 and sum(prob) == 1.\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003c/w:body\u003e\u003c/w:document\u003e\"},{\"partUri\":\"/matlab/output.xml\",\"contentType\":\"text/xml\",\"content\":\"\u003c?xml version=\\\"1.0\\\" encoding=\\\"UTF-8\\\" standalone=\\\"no\\\" ?\u003e\u003cembeddedOutputs\u003e\u003cmetaData\u003e\u003cevaluationState\u003emanual\u003c/evaluationState\u003e\u003clayoutState\u003ecode\u003c/layoutState\u003e\u003coutputStatus\u003eready\u003c/outputStatus\u003e\u003c/metaData\u003e\u003coutputArray type=\\\"array\\\"/\u003e\u003cregionArray type=\\\"array\\\"/\u003e\u003c/embeddedOutputs\u003e\"}]}"}],"errors":[],"facets":[[{"value":"Probability \u0026 Stats","count":1,"selected":false},{"value":"Randomness","count":1,"selected":false}],[{"value":"hard","count":1,"selected":false}]],"term":"tag:\"random sampling\"","page":1,"per_page":50,"sort":"map(difficulty_value,0,0,999) asc"}}