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

Created by Peng Liu

Solve Later

{"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>

Solve

Solution Stats

18 Solutions
10 Solvers

Last Solution submitted on May 05, 2021

Last 200 Solutions

Problem Comments

Problem Recent Solvers10

Problem Tags

array structfun structure

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

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

Solution Stats

Last 200 Solutions

Problem Comments

Problem Recent Solvers10

Suggested Problems

More from this Author30

Problem Tags

Community Treasure Hunt

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

Solution Stats

Last 200 Solutions

Problem Comments

Problem Recent Solvers10

Suggested Problems

More from this Author30

Problem Tags

Community Treasure Hunt

Players