Problem 43685. Apply Function to Each Field of a Structure Array: Part 1

Created by Peng Liu

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{"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":"<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<w:document xmlns:w=\"http://schemas.openxmlformats.org/wordprocessingml/2006/main\"><w:body><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>The builtin</w:t></w:r><w:r><w:t> </w:t></w:r><w:hyperlink w:docLocation=\"http://www.mathworks.com/help/matlab/ref/structfun.html?=structfun\"><w:r><w:t>structfun</w:t></w:r></w:hyperlink><w:r><w:t> applies a function handle to each field of a</w:t></w:r><w:r><w:t> </w:t></w:r><w:r><w:rPr><w:b/></w:rPr><w:t>scalar structure</w:t></w:r><w:r><w:t>, but it does not work for structure array. The purpose of this problem is to generalize structfun to enable support for structure array input.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>Write your own function</w:t></w:r><w:r><w:t> </w:t></w:r><w:r><w:rPr><w:b/></w:rPr><w:t>structfun2</w:t></w:r><w:r><w:t> which accepts a structure array</w:t></w:r><w:r><w:t> </w:t></w:r><w:r><w:rPr><w:b/></w:rPr><w:t>s</w:t></w:r><w:r><w:t> and a function handle</w:t></w:r><w:r><w:t> </w:t></w:r><w:r><w:rPr><w:b/></w:rPr><w:t>f</w:t></w:r><w:r><w:t> as the inputs. The output</w:t></w:r><w:r><w:t> </w:t></w:r><w:r><w:rPr><w:b/></w:rPr><w:t>c = structfun2(f,s)</w:t></w:r><w:r><w:t> is a cell array of the same size as</w:t></w:r><w:r><w:t> </w:t></w:r><w:r><w:rPr><w:b/></w:rPr><w:t>s</w:t></w:r><w:r><w:t>, with each cell storing the result of</w:t></w:r><w:r><w:t> </w:t></w:r><w:r><w:rPr><w:b/></w:rPr><w:t>f</w:t></w:r><w:r><w:t> applied to every field of the relevant structure element in</w:t></w:r><w:r><w:t> </w:t></w:r><w:r><w:rPr><w:b/></w:rPr><w:t>s</w:t></w:r><w:r><w:t>. The structfun2 must preserve the behavior of structfun for scalar structure input. That is, structfun2(f,s) = structfun(f,s) holds for any scalar structure</w:t></w:r><w:r><w:t> </w:t></w:r><w:r><w:rPr><w:b/></w:rPr><w:t>s</w:t></w:r><w:r><w:t>. The assumption required is that</w:t></w:r><w:r><w:t> </w:t></w:r><w:r><w:rPr><w:b/></w:rPr><w:t>f</w:t></w:r><w:r><w:t> is a function that returns a scalar, regardless of the input.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>Example:</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"code\"/></w:pPr><w:r><w:t><![CDATA[s = struct('f1',{1, [3 4]; 1, [5 6]},'f2',{[1 2], 2; [3 4 5], [2 5]});\nf = @numel;\nc = {[1;2], [2;1]; [1;3], [2;2]};]]></w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>Related problems in this series:</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"ListParagraph\"/><w:numPr><w:numId w:val=\"1\"/></w:numPr></w:pPr><w:hyperlink w:docLocation=\"http://www.mathworks.com/matlabcentral/cody/problems/43686-apply-function-to-each-field-of-a-structure-array-part-2\"><w:r><w:t>Apply Function to Each Field of a Structure Array: Part 2</w:t></w:r></w:hyperlink></w:p><w:p><w:pPr><w:pStyle w:val=\"ListParagraph\"/><w:numPr><w:numId w:val=\"1\"/></w:numPr></w:pPr><w:hyperlink w:docLocation=\"http://www.mathworks.com/matlabcentral/cody/problems/43685-apply-function-to-each-field-of-a-structure-array-part-1\"><w:r><w:t>Apply Function to Each Field of a Structure Array: Part 1</w:t></w:r></w:hyperlink></w:p></w:body></w:document>"},{"partUri":"/matlab/output.xml","contentType":"text/xml","content":"<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"no\" ?><embeddedOutputs><metaData><evaluationState>manual</evaluationState><layoutState>code</layoutState><outputStatus>ready</outputStatus></metaData><outputArray type=\"array\"/><regionArray type=\"array\"/></embeddedOutputs>"}]}

The builtin <a href = "http://www.mathworks.com/help/matlab/ref/structfun.html?=structfun">structfun</a> applies a function handle to each field of a scalar structure, but it does not work for structure array. The purpose of this problem is to generalize structfun to enable support for structure array input.Write your own function structfun2 which accepts a structure array s and a function handle f as the inputs. The output c = structfun2(f,s) is a cell array of the same size as s, with each cell storing the result of f applied to every field of the relevant structure element in s. The structfun2 must preserve the behavior of structfun for scalar structure input. That is, structfun2(f,s) = structfun(f,s) holds for any scalar structure s. The assumption required is that f is a function that returns a scalar, regardless of the input.Example:<pre class="language-matlab">s = struct('f1',{1, [3 4]; 1, [5 6]},'f2',{[1 2], 2; [3 4 5], [2 5]});
f = @numel;
c = {[1;2], [2;1]; [1;3], [2;2]};
</pre>Related problems in this series:<ul><li><a href = "http://www.mathworks.com/matlabcentral/cody/problems/43686-apply-function-to-each-field-of-a-structure-array-part-2">Apply Function to Each Field of a Structure Array: Part 2</a></li><li><a href = "http://www.mathworks.com/matlabcentral/cody/problems/43685-apply-function-to-each-field-of-a-structure-array-part-1">Apply Function to Each Field of a Structure Array: Part 1</a></li></ul>

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Problem 43685. Apply Function to Each Field of a Structure Array: Part 1

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Problem 43685. Apply Function to Each Field of a Structure Array: Part 1

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