How to find repeated cell vectors in matlab?

Question

I have n different length cell vectors, call it c{i} , i=1,2,...,n.

I wanna find those c{i} which equal with others, for example:

c{1}=[1 2 3 4 5 6]; c{2}=[1 3 5 7]; c{3}=[2 4 6 8];
c{4}=[1 4 6]; c{5}=[3 7]; c{6}=[2 4 6 8]; c{7}=[1 3 5 7];

I hope I can find [2 4 6 8] and [1 3 5 7] with a simple way instead of using two loops.

Thanks!

Answer 1

You can do it with unique . You need to convert vectors to strings, because unique works with cell arrays of strings but not with cell arrays of numeric vectors. After unique , you can count how many strings (vector) are repeated with histc , and them some indexing lets you retrieve the corresponding vectors:

strcell = cellfun(@(e) num2str(e), c, 'uniformoutput', 0); %// convert to strings
[~, ii, jj] = unique(strcell); %// apply unique. Second and third outputs needed
ind = find(histc(jj,min(jj)-.5:max(jj)+.2)>1); %// which appear more than once
result = c(ii(ind)); %// indexing to obtain corresponding original vectors