Finding strings using an index

i have character array list , wish tally number of substring occurrences against index held in numerical vector chr:

list = ccnncccnnncnncn  chr =       1      1      1      1      2      2      2      2      2      2      2      2      2      2      2

ordinarily, searching adjacent string pairs i.e. 'nn' , utilise method:

count(:,1) = accumarray(chr(intersect([strfind(list,'cc')],find(~diff(chr)))),1);

using ~diff(chr) ensure pattern matching not cross index boundaries.

however, want match single letter strings i.e. 'n' - how can accomplish this? above method means last letter in each index missed , not counted.

the desired result above example 2 column matrix detailing number of 'c's , 'n's within each index:

c     n 2     2 5     6

i.e. there 2c's , 2n's within index '1' (stored in chr) - count restarts 0 next '2' - there 5c's , 6n's.

[u, ~, v] = unique(list);          %// unique labels list in variable v result = full(sparse(chr, v, 1));  %// accumulate combinations of chr , v

this works arbitrary number of letters in list, arbitrary number of indices in chr, , chr not sorted.

in example

list = 'ccnncccnnncnncn'; chr = [1 1 1 1 2 2 2 2 2 2 2 2 2 2 2].';

which produces

result =      2     2      5     6

the letter associated each column of result given u:

u = cn

Core code