Can I use UNIQUE to get a count of the number of times each element is repeated?

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MathWorks Support Team
回答： Lola Davidson 2022-9-6
I would like to know if the UNIQUE function has the capability of returning the number of times each element appears in an array.

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采纳的回答

MathWorks Support Team
The ability to return the count of each unique element is not available in the UNIQUE function in MATLAB.
To work around this issue, use the ARRAYFUN function to test each element of an array, determining the number of times each element is equal to an element of original vector.
For example:
a = [12 34 78 8 12 3 34 34];
c = arrayfun(@(x)length(find(a == x)), unique(a), 'Uniform', false);
cell2mat(c)

更多回答（1 个）

Lola Davidson
Lola Davidson 2022-9-6
As of R2019a, you can use groupcounts for this:
>> a = [12 34 78 8 12 3 34 34]';
>> [counts, groupnames] = groupcounts(a)
counts =
1
1
2
3
1
groupnames =
3
8
12
34
78

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