Count number of letter repetitions in a string - matlab

Question

I am trying to find how many times each letter appears in a cell array.
I have to open this data file in Matlab
A 12 A 88
B 23 F 22
C 55 B 77
D 66 H 44
I named it Thor.dat and this is my code in Matlab
fid = fopen('Thor.dat')
if fid == -1
disp ('File open not successful')
else
disp ('File open is successful')
mat = textscan(fid,'%c %f %c %f')
[r c] = size(mat)
charoccur(mat)
fclose(fid)
end
and the charoccur function is
function occurence = charoccur(mat)
% charoccur finds the number of times each character appears in a column
[row, col] = size(mat);
[row, ccol] = size(mat{1});
[mat] = unique(mat{i})
d = hist(c,length(a))
end

Answer 1

Here is a way to do it using unique and strcmp. Basically loop though the cell array and sum the number of occurence of each unique letters. Using strcmp gives a logical array of 0 and 1. By summing the 1s you get the total number of times a letter is found.
clear
clc
%// Input cell array
mat = {'A' 12 'A' 88;'B' 23 'F' 22;'C' 55 'B' 77;'D' 66 'H' 44;'W' 11 'C' 9;'H' 3 'H' 0};
mat = [mat(:,1) mat(:,3)]
%// Find unique letters
UniqueLetters = unique(mat);
%// Initialize output cell
OutputCell = cell(numel(UniqueLetters,2));
%// Loop through each unique letter and count number of occurence
for k = 1:numel(UniqueLetters);
%// 1st column: letter
OutputCell(k,1) = UniqueLetters(k);
%// 2nd column: sum of occurences
OutputCell(k,2) = {sum(sum(strcmp(UniqueLetters{k},mat)))};
end
OutputCell
OutputCell now looks like this:
OutputCell =
'A' [2]
'B' [2]
'C' [2]
'D' [1]
'F' [1]
'H' [3]
'W' [1]
Hope that helps get you started!
EDIT:
As per your comment, for the initialization of the output cell array:
OutputCell = cell(numel(UniqueLetters,2));
I create a Nx2 cell array, in which N (the number of rows) is the number of unique cells identified by the call to unique. In my example above there are 7 unique letters, so I create a 7x2 cell array to store:
1) In column 1 the actual letter
2) In column 2 the number of times this letter is found in mat