如何计算matlab中单元的独特元素？

Question

我想在Matlab中计算单元阵列的独特元素。我怎样才能做到这一点？谢谢。

c = {'a', 'b', 'c', 'a'}; 
% count unique elements, return the following struct 
unique_count.a = 2 
unique_count.b = 1 
unique_count.c = 1 

Answer 1

要算独特的元素，你可以用ACCUMARRAY

c = {'a', 'b', 'c', 'a'}; 
[uniqueC,~,idx] = unique(c); %# uniqueC are unique entries in c 
          %# replace the tilde with 'dummy' if pre-R2008a 

counts = accumarray(idx(:),1,[],@sum); 

结合UNIQUE为了生产结构，使用NUM2CELL和STRUCT：对文件交换

countCell = num2cell(counts); 
tmp = [uniqueC;countCell']; %' 

unique_count = struct(tmp{:}) %# this evaluates to struct('a',2,'b',1,'c') 

unique_count = 
    a: 2 
    b: 1 
    c: 1 

Answer 2

退房count_unique。它使用accumarray或sort，这取决于哪一个最合适。它也会检查nans/infs。