How to access elements with same field names in an array of structures without using a loop?
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Hello,
Assume we have a cell array of structures:
a.name = 'first';
b.name = 'second';
c.name = 'third';
s = {a; b; c};
Now I want to change the values of fields "name" in some specific structures, for example, in 1 and 3. I know how to do it using a "for"-loop:
ind = [1,3];
replacement = {'whatever', 'word'};
for i = 1:length(ind)
s{ind(i)}.name = replacement{i};
end
Is there a way to do it without a loop? I have found a similar question, but there the author was interested in extracting the data, not in replacing them. Frankly, I am bad in both writing and reading handles' syntaxis, so maybe this answer can be applied to my problem as well, and I just do not see how. Plus, as was mentioned in the comments, cellfun is not faster than a loop - and, at least for me, not easier to read either.
3 个评论
Stephen23
2026-9-17，16:41
What are "handles" ?
Paul
2026-9-17，23:21
Is there an objection to using a for loop?
Wassili Dimitriew
2026-9-18，7:36
采纳的回答
"How to access elements with same field names in an array of structures without using a loop?"
There is no way using your data, because you actually showed a cell array of scalar structures (which is not very good data design if all of the scalar structures have the same fields). Much better would be to use a non-scalar structure array:
s(1).name = 'first';
s(2).name = 'second';
s(3).name = 'third';
s.name % checking
in which case your request is certainly possible:
idx = [1,3];
rpl = {'whatever', 'word'};
[s(idx).name] = deal(rpl{:});
s.name % checking
For more information:
6 个评论
However a cell array of scalar structures (like you showed) will not work:
a.name = 'first';
b.name = 'second';
c.name = 'third';
ThisIsACellArrayNotAStructureArray = {a; b; c};
idx = [1,3];
rpl = {'whatever', 'word'};
[ThisIsACellArrayNotAStructureArray{idx}.name] = deal(rpl{:});
for the reasons explained here:
(the explanation is generally valid for any nested container arrays, not just structure arrays).
Wassili Dimitriew
2026-9-17，12:38
"I cannot be sure that all the structures have the same number/positioning of fields"
Only the fieldnames are really relevant.
If you prefer to stick with scalar structures in a cell array then you will have to use an implict or explicit loop.
See also:
Wassili Dimitriew
2026-9-18，7:38
dpb
2026-9-18，14:22
"I cannot be sure that all the structures have the same number/positioning of fields"
Perhaps instead of the cell array of disparate but apparently somehow related scalar struct, use a nested struct that incorporates the alternate data fields by what identifies the particular quantities? <Address Nested Structures>
Wassili Dimitriew
44 minutes 前
编辑：Wassili Dimitriew
43 minutes 前
更多回答（1 个）
Walter Roberson
2026-9-17，17:20
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1 个评论
Rik
2026-9-18，19:39
And also this suggestion comes with the caveat that it will be slower than a loop, have more overhead, and will be harder to maintain/update or debug.
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