Zero out values in multiple fields of a struct

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Rich006
Rich006 2023-5-5
编辑： Matt J 2023-5-8
Suppose I have
S.ABC0500 = struct('Keys',[1:9],'Values',rand(1,9));
S.ABC0800 = struct('Keys',[1:9],'Values',rand(1,9));
S.ABC0900 = struct('Keys',[1:9],'Values',rand(1,9));
S.Title = 'MyData';
S.Date = datetime('today');
How can I efficiently set all the values to zero? That is, I want to do
S.ABC0500.Values = zeros(1,9);
S.ABC0800.Values = zeros(1,9);
S.ABC0900.Values = zeros(1,9);
The number of ABC variables is large.
  1 个评论
Stephen23
Stephen23 2023-5-5
"How can I efficiently set all the values to zero"
With more suitable data design: don't force meta-data into fieldnames. A non-scalar structure would likely be better:
https://www.mathworks.com/help/matlab/matlab_prog/access-multiple-elements-of-a-nonscalar-struct-array.html

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采纳的回答

Rich006
Rich006 2023-5-8
I have found my own answer, but there's probably a more elegant way.
fn = fieldnames(S); % array of S field names including the ABC variables
idx = regexp(fn,'ABC*'); % cell array of 1 or [] depending on whether fn matches 'ABC*'
for k=1:length(fn)
if idx{k}
S.(fn{k}).Values = zeros(1,9);
end
end
  1 个评论
Matt J
Matt J 2023-5-8
编辑：Matt J 2023-5-8
I would simplify this to,
fn = fieldnames(S);
fn=fn( startsWith( fn ,"ABC"));
for k=1:length(fn)
S.(fn{k}).Values(:) = 0;
end
In particular, avoiding repeated calls to zeros() should speed things up a bit.

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更多回答（1 个）

Matt J
Matt J 2023-5-5
编辑：Matt J 2023-5-5
I would recommend a different data organization:
S.Title = 'MyData';
S.Date = datetime('today');
S.ID=["ABC0500", "ABC0500", "ABC0900"]';
S.Values=rand(3,9);
S.Keys=repmat(1:9,3,1);
and then you can simply do,
S.Values(:)=0;
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Rich006
Rich006 2023-5-8
I guess when I said "efficiently" I meant without having to write a separate command for each variable. I only need to do this one time, so speed of execution isn't that important.

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