countEntries.m

function [uniqueEntries,numberOfOccurences,whereIdx] = countEntries(m,isRow, keepNaN)
%COUNTENTRIES returns all unique entries (sorted) in the array m and how many times the respective entries occured
%
%SYNOPSIS [uniqueEntries,numberOfOccurences] = countEntries(m,isRow)
%
%INPUT  m          : any matrix (not cells or structs)
%       isRow(opt) : should rows be counted or not [1/{0}]
%                       (if it's cols, transpose m before calling the function!)
%       keepNaN (opt) : count NaN as entry? [{1}/0] If 0, NaNs (or
%                       NaN-containing rows) are removed after sorting, so
%                       that whereIdx still refers to the original position
%                       of the uniqueEntries in the input array.
%
%OUTPUT uniqueEntries : unique(m)
%       numberOfOccurences : how many times the unique entries appear in m
%       whereIdx      : where in m do the entries appear? (m = uniqueEntries(whereIdx,:))
%
%c: 11/03, jonas
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


%---test input
if iscell(m) || isstruct(m)
    error('cells and structs are not supportet as input');
end

if nargin < 2 || isempty(isRow)
    doRow = 0;
else
    if isRow == 1;
        doRow = 1;
    elseif isRow == 0
        doRow = 0;
    else
        error('input argument isRow has to be 1 or 0!')
    end
end
if nargin < 3 || isempty(keepNaN)
    keepNaN = true;
end
%---end test input



if ~doRow %do the fast method
    
    %make m into a vector
    m = m(:);
    
    %get unique Entries. sort them first, though
    m = sort(m);
    
    [uniqueEntries, uniqueIdx, whereIdx] = unique(m);
    
    if ~keepNaN
        % remove NaN, inf
        badIdx = find(~isfinite(uniqueEntries));
        uniqueEntries(badIdx) = [];
        uniqueIdx(badIdx) = [];
        whereIdx(ismember(whereIdx,badIdx)) = [];
    end
    
    %uniqueIdx returns the last occurence of the respective unique entry
    %having sorted m before, we can now count the number of occurences
    if size(uniqueEntries,1)>size(uniqueEntries,2)
        uniqueIdx = [0;uniqueIdx];
    else
        uniqueIdx = [0,uniqueIdx];
    end
    
    numberOfOccurences = diff(uniqueIdx); 
    
else %do it the complicated way
    
    %we do not care about the ordering of the matrix here: if the user
    %specified rows, he/she wanted a columnVector as output (or should read the help)
    [uniqueEntries, dummy, uniqueIdx] = unique(m,'rows');
    
    %rember output
    whereIdx = uniqueIdx;
    
    if ~keepNaN
        % remove NaN, inf
        badIdx = find(any(~isfinite(uniqueEntries),2));
        uniqueEntries(badIdx,:) = [];
        whereIdx(ismember(whereIdx,badIdx)) = [];
        uniqueIdx = whereIdx;
    end
    
    %uniqueIdx returns the indexList where uniqueEntriy #x occurs.
    %We will now sort this list and take a diff to find where this index
    %changes.
    %adding zero and length(uniqueIndex) to the vector, we can now via
    %another diff see how many entries there are (see example)
    
    %example m: [11,11,22,33,33,22,22,22,44,11]
    %corresponding uniqueEntries, uniqueIdx: [11,22,33,44] / [1 1 2 3 3 2 2 2 4 1]
    
    %sort: [1     1     1     2     2     2     2     3     3     4]
    sortedIdx = sort(uniqueIdx);
    
    %diff: [0     0     1     0     0     0     1     0     1]
    sortedIdxDiff = diff(sortedIdx);
    
    %find and add entries: [0     3     7     9    10]
    changeValueIdx = [0;find(sortedIdxDiff);length(uniqueIdx)];
    
    %diff again for the numberOfOccurences: [3     4     2     1]
    numberOfOccurences = diff(changeValueIdx);
end