{"group":{"id":1,"name":"Community","lockable":false,"created_at":"2012-01-18T18:02:15.000Z","updated_at":"2026-05-26T00:16:20.000Z","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":"2026-05-26T00:00:00.000Z","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":42858,"title":"Block average ignoring NaN values","description":"Given a matrix, calculate the block average of each disjoint sub-matrix while ignoring *NaN* values. Assume that the size of the matrix along each dimension is an integer multiple of the size of the sub-matrix along the same dimension.\r\n\r\n* Input: matrix *A* and the size of each sub-matrix *subsz*\r\n* Output: *B = blknanavg(A,subsz)*\r\n    \r\n\r\nExample:\r\n\r\n    A = [1 2 3 4 5 6 7 8 NaN];\r\n    subsz = [1  3];\r\n    B = [2  5  (7+8)/2];\r\n\r\nHint: this is related to \u003chttp://www.mathworks.com/matlabcentral/cody/problems/42856-block-average Problem 42856. Block average\u003e.","description_html":"\u003cp\u003eGiven a matrix, calculate the block average of each disjoint sub-matrix while ignoring \u003cb\u003eNaN\u003c/b\u003e values. Assume that the size of the matrix along each dimension is an integer multiple of the size of the sub-matrix along the same dimension.\u003c/p\u003e\u003cul\u003e\u003cli\u003eInput: matrix \u003cb\u003eA\u003c/b\u003e and the size of each sub-matrix \u003cb\u003esubsz\u003c/b\u003e\u003c/li\u003e\u003cli\u003eOutput: \u003cb\u003eB = blknanavg(A,subsz)\u003c/b\u003e\u003c/li\u003e\u003c/ul\u003e\u003cp\u003eExample:\u003c/p\u003e\u003cpre\u003e    A = [1 2 3 4 5 6 7 8 NaN];\r\n    subsz = [1  3];\r\n    B = [2  5  (7+8)/2];\u003c/pre\u003e\u003cp\u003eHint: this is related to \u003ca href = \"http://www.mathworks.com/matlabcentral/cody/problems/42856-block-average\"\u003eProblem 42856. Block average\u003c/a\u003e.\u003c/p\u003e","function_template":"function B = blknanavg(A)\r\n  B = A;\r\nend","test_suite":"%%\r\nA = [1 2 3 4 5 6 7 8 NaN];\r\nsubsz = [1  3];\r\nB = [2  5  (7+8)/2];\r\nassert(norm(B-blknanavg(A,subsz)) \u003c 1e-10)\r\n\r\n%%\r\nA = [1 2 3 4 NaN 6 7 NaN 9].';\r\nsubsz = [3,1];\r\nB = [2 5 8].';\r\nassert(norm(B-blknanavg(A,subsz)) \u003c 1e-10)\r\n\r\n%%\r\nA = [1       1     1       2     NaN       2\r\n     1     NaN     1     NaN       2     NaN\r\n     3       3     3     NaN     NaN     4\r\n     3       3     3     NaN       4     4];\r\nsubsz = [2   3];\r\nB = [1    2\r\n     3    4];\r\nassert(norm(B-blknanavg(A,subsz)) \u003c 1e-10)\r\n\r\n%%\r\nA = rand(100,300);\r\nA(randperm(numel(A),10)) = NaN;\r\nsubsz = size(A);\r\nB = mean(A(:),'omitnan');\r\nassert(norm(B-blknanavg(A,subsz)) \u003c 1e-10)\r\n\r\n%%\r\nsubsz = [4,6];\r\nB = 10*rand(10,20);\r\nA = repelem(B,subsz(1),subsz(2));\r\nA(randperm(numel(A),10)) = NaN;\r\nassert(norm(B-blknanavg(A,subsz)) \u003c 1e-10)","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":44,"test_suite_updated_at":null,"rescore_all_solutions":false,"group_id":24,"created_at":"2016-05-21T19:53:06.000Z","updated_at":"2026-05-04T19:29:43.000Z","published_at":"2016-05-21T20:04:51.000Z","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\u003eGiven a matrix, calculate the block average of each disjoint sub-matrix while ignoring\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e \u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:rPr\u003e\u003cw:b/\u003e\u003c/w:rPr\u003e\u003cw:t\u003eNaN\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e values. Assume that the size of the matrix along each dimension is an integer multiple of the size of the sub-matrix along the same dimension.\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"ListParagraph\\\"/\u003e\u003cw:numPr\u003e\u003cw:numId w:val=\\\"1\\\"/\u003e\u003c/w:numPr\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eInput: matrix\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e \u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:rPr\u003e\u003cw:b/\u003e\u003c/w:rPr\u003e\u003cw:t\u003eA\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e and the size of each sub-matrix\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e \u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:rPr\u003e\u003cw:b/\u003e\u003c/w:rPr\u003e\u003cw:t\u003esubsz\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"ListParagraph\\\"/\u003e\u003cw:numPr\u003e\u003cw:numId w:val=\\\"1\\\"/\u003e\u003c/w:numPr\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eOutput:\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e \u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:rPr\u003e\u003cw:b/\u003e\u003c/w:rPr\u003e\u003cw:t\u003eB = blknanavg(A,subsz)\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\u003eExample:\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[    A = [1 2 3 4 5 6 7 8 NaN];\\n    subsz = [1  3];\\n    B = [2  5  (7+8)/2];]]\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\u003eHint: this is related to\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/42856-block-average\\\"\u003e\u003cw:r\u003e\u003cw:t\u003eProblem 42856. Block average\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:hyperlink\u003e\u003cw:r\u003e\u003cw:t\u003e.\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":42858,"title":"Block average ignoring NaN values","description":"Given a matrix, calculate the block average of each disjoint sub-matrix while ignoring *NaN* values. Assume that the size of the matrix along each dimension is an integer multiple of the size of the sub-matrix along the same dimension.\r\n\r\n* Input: matrix *A* and the size of each sub-matrix *subsz*\r\n* Output: *B = blknanavg(A,subsz)*\r\n    \r\n\r\nExample:\r\n\r\n    A = [1 2 3 4 5 6 7 8 NaN];\r\n    subsz = [1  3];\r\n    B = [2  5  (7+8)/2];\r\n\r\nHint: this is related to \u003chttp://www.mathworks.com/matlabcentral/cody/problems/42856-block-average Problem 42856. Block average\u003e.","description_html":"\u003cp\u003eGiven a matrix, calculate the block average of each disjoint sub-matrix while ignoring \u003cb\u003eNaN\u003c/b\u003e values. Assume that the size of the matrix along each dimension is an integer multiple of the size of the sub-matrix along the same dimension.\u003c/p\u003e\u003cul\u003e\u003cli\u003eInput: matrix \u003cb\u003eA\u003c/b\u003e and the size of each sub-matrix \u003cb\u003esubsz\u003c/b\u003e\u003c/li\u003e\u003cli\u003eOutput: \u003cb\u003eB = blknanavg(A,subsz)\u003c/b\u003e\u003c/li\u003e\u003c/ul\u003e\u003cp\u003eExample:\u003c/p\u003e\u003cpre\u003e    A = [1 2 3 4 5 6 7 8 NaN];\r\n    subsz = [1  3];\r\n    B = [2  5  (7+8)/2];\u003c/pre\u003e\u003cp\u003eHint: this is related to \u003ca href = \"http://www.mathworks.com/matlabcentral/cody/problems/42856-block-average\"\u003eProblem 42856. Block average\u003c/a\u003e.\u003c/p\u003e","function_template":"function B = blknanavg(A)\r\n  B = A;\r\nend","test_suite":"%%\r\nA = [1 2 3 4 5 6 7 8 NaN];\r\nsubsz = [1  3];\r\nB = [2  5  (7+8)/2];\r\nassert(norm(B-blknanavg(A,subsz)) \u003c 1e-10)\r\n\r\n%%\r\nA = [1 2 3 4 NaN 6 7 NaN 9].';\r\nsubsz = [3,1];\r\nB = [2 5 8].';\r\nassert(norm(B-blknanavg(A,subsz)) \u003c 1e-10)\r\n\r\n%%\r\nA = [1       1     1       2     NaN       2\r\n     1     NaN     1     NaN       2     NaN\r\n     3       3     3     NaN     NaN     4\r\n     3       3     3     NaN       4     4];\r\nsubsz = [2   3];\r\nB = [1    2\r\n     3    4];\r\nassert(norm(B-blknanavg(A,subsz)) \u003c 1e-10)\r\n\r\n%%\r\nA = rand(100,300);\r\nA(randperm(numel(A),10)) = NaN;\r\nsubsz = size(A);\r\nB = mean(A(:),'omitnan');\r\nassert(norm(B-blknanavg(A,subsz)) \u003c 1e-10)\r\n\r\n%%\r\nsubsz = [4,6];\r\nB = 10*rand(10,20);\r\nA = repelem(B,subsz(1),subsz(2));\r\nA(randperm(numel(A),10)) = NaN;\r\nassert(norm(B-blknanavg(A,subsz)) \u003c 1e-10)","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":44,"test_suite_updated_at":null,"rescore_all_solutions":false,"group_id":24,"created_at":"2016-05-21T19:53:06.000Z","updated_at":"2026-05-04T19:29:43.000Z","published_at":"2016-05-21T20:04:51.000Z","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\u003eGiven a matrix, calculate the block average of each disjoint sub-matrix while ignoring\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e \u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:rPr\u003e\u003cw:b/\u003e\u003c/w:rPr\u003e\u003cw:t\u003eNaN\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e values. Assume that the size of the matrix along each dimension is an integer multiple of the size of the sub-matrix along the same dimension.\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"ListParagraph\\\"/\u003e\u003cw:numPr\u003e\u003cw:numId w:val=\\\"1\\\"/\u003e\u003c/w:numPr\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eInput: matrix\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e \u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:rPr\u003e\u003cw:b/\u003e\u003c/w:rPr\u003e\u003cw:t\u003eA\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e and the size of each sub-matrix\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e \u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:rPr\u003e\u003cw:b/\u003e\u003c/w:rPr\u003e\u003cw:t\u003esubsz\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:p\u003e\u003cw:p\u003e\u003cw:pPr\u003e\u003cw:pStyle w:val=\\\"ListParagraph\\\"/\u003e\u003cw:numPr\u003e\u003cw:numId w:val=\\\"1\\\"/\u003e\u003c/w:numPr\u003e\u003c/w:pPr\u003e\u003cw:r\u003e\u003cw:t\u003eOutput:\u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:t\u003e \u003c/w:t\u003e\u003c/w:r\u003e\u003cw:r\u003e\u003cw:rPr\u003e\u003cw:b/\u003e\u003c/w:rPr\u003e\u003cw:t\u003eB = blknanavg(A,subsz)\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\u003eExample:\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[    A = [1 2 3 4 5 6 7 8 NaN];\\n    subsz = [1  3];\\n    B = [2  5  (7+8)/2];]]\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\u003eHint: this is related to\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/42856-block-average\\\"\u003e\u003cw:r\u003e\u003cw:t\u003eProblem 42856. Block average\u003c/w:t\u003e\u003c/w:r\u003e\u003c/w:hyperlink\u003e\u003cw:r\u003e\u003cw:t\u003e.\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":"Matrix Manipulation III","count":1,"selected":false}],[{"value":"medium","count":1,"selected":false}]],"term":"tag:\"block average\"","page":1,"per_page":50,"sort":"map(difficulty_value,0,0,999) asc"}}