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Count the number of occurrences in a string vector

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buhmatlab
buhmatlab on 7 Apr 2020
Edited: Andrei Bobrov on 7 Apr 2020
Hi,
I'm relatively new to Matlab because I only used Excel so far. For my project I used the COUNTIFS function and I'm wondering how to do this in Matlab.
Say I've got a column vector 300x1:
I want to create a vector of the same size that counts and sums up each entry.
Example:
If my entries are A;A;B;A;B;B;C;A;C the new vector should look like: 1;2;1;3;2;3;1;4;2
Thank you so much!

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Accepted Answer

Andrei Bobrov
Andrei Bobrov on 7 Apr 2020
Edited: Andrei Bobrov on 7 Apr 2020
s = string({'A';'A';'B';'A';'B';'B';'C';'A';'C'});
out = zeros(numel(s),1);
[~,~,c] = unique(s);
for i = 1:max(c)
lo = c == i;
out(lo) = 1:sum(lo);
end
or
[~,~,c] = unique(s);
z = c == (1:max(c)); % or use here: z = bsxfun(@eq,c,1:max(c));
out = sum(cumsum(z).*z,2);
I'm use R2016b.

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buhmatlab
buhmatlab on 7 Apr 2020
This works perfectly! I wonder how long it would have taken for me to figure this out...
THANK YOU!!!

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