How can I perform a union with two single-field Matlab structs

Question

I currently have two single-field Matlab structs that list image names. I would like to combine them into a single struct with no duplicates - i.e.

a(1).img = 'aa.jpg'
a(2).img = 'bb.jpg'

b(1).img = 'bb.jpg'
b(2).img = 'cc.jpg'

I would like for ab to have value(s):

ab(1) = 'aa.jpg'
ab(2) = 'bb.jpg'
ab(3) = 'cc.jpg'

Is there a non=brute force way of doing this?

Suever · Accepted Answer · 2016-07-22T18:51:40.087

3

You can concatenate the values from each of the structs using a comma-separated list followed by unique to get the unique values. Then, passing this to the struct function will create an array of structs containing the values.

S = struct('img', unique({a.img, b.img}, 'stable'))

If you don't actually need a struct out and just want a cell array of the unique values, you can eliminate the final call to struct.

unique({a.img, b.img}, 'stable')

edited Jul 22 '16 at 18:51

answered Jul 22 '16 at 18:45

Suever

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@LuisMendo Yea that should work as well. Probably a bit cleaner – Suever Jul 22 '16 at 18:49
I've actually just used: `unique({a(:).img, b(:).img})` – user1245262 Jul 22 '16 at 18:50
@user1245262 In this context, the `(:)` is unnecessary – Suever Jul 22 '16 at 18:52
@Suever - Thanks. What does the 'stable' argument do? – user1245262 Jul 22 '16 at 18:53
2

@user1245262 By default `unique` will sort the values. `'stable'` ensures that they remain in the order that they first appeared. – Suever Jul 22 '16 at 18:54

How can I perform a union with two single-field Matlab structs

1 Answers1