Say that I have two cell arrays, A and B, that contain string values. I wish to populate a struct S such I generate every possible combination of S.valueinA.valueinB = 1. I am currently trying to accomplish this with two nested for-loops that iterate through every possible combination and wanted to ask if there is a more efficient way to solve this problem in MATLAB.
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1 Answer
If you want to make dynamic field names in structures, I don't see how else you can do it without two for loops. Let's say we have two cell arrays A and B that consist of string entries.
For my example, apologies for the strings inside these arrays in advance as I couldn't think of anything better at the moment!
Is this what you're trying to achieve?
S = struct();
A = {'hello', 'my', 'name', 'is', 'ray'};
B = {'i', 'am', 'doing', 'awesome'};
for idx = 1 : numel(A)
for idx2 = 1 : numel(B)
S.(A{idx}).(B{idx2}) = 1;
end
end
This creates a nested structure S such that for each element in A, this becomes a field in S where this field is another structure that contains fields with names coming from all elements in B.
If we displayed S, we get:
>> S
S =
hello: [1x1 struct]
my: [1x1 struct]
name: [1x1 struct]
is: [1x1 struct]
ray: [1x1 struct]
If we accessed the hello field of S, we get:
>> S.hello
ans =
i: 1
am: 1
doing: 1
awesome: 1
Similarly, if we accessed the my field, we get:
>> S.my
ans =
i: 1
am: 1
doing: 1
awesome: 1
Therefore, if we want to get the hello field followed by the am field, we do:
>> S.hello.am
ans =
1
3 Comments
rayryeng
@nkjt - lol. thank you very much. that comment made my morning.
osm
@rayryeng Thanks for the answer! This is in fact what I was trying to achieve; I was trying to research whether matlab had a more efficient method (since this could take really long over thousands of entries).
rayryeng
@mCode - Ah I gotcha. Yeah when it comes to dynamic field names, I don't see how you could do this without a
for loop. However, if the nested field consists of just a single number, then I think it should be relatively fast. I haven't tested it yet, but that's my hunch. You're welcome btw!