how to get the most repeated element of a cell array?

i have an cell array like this

 {[];[];[];[];[];[];[];[];'rj';'rj';'rj';'rj';'rj';'rj';'rj';'rj';'rj';'rj';'rj';'rj';'rj';'rj';}

is there a way to get the label of this array as rj?

[Cedric]

Is the content either empty or equal to the same string? What happens if there are more empty cells than cells containing strings?

[Matt J]

maybe i did ask the question wrong, but if i have more {''} it will give me that name. instead i want {'rj'}. is there a workaround to counting?

Yes, you'll need to clarify the question. Why should {''} be ignored? Are there any other strings that should be ignored?

[the cyclist]

In other words, you need to provide a more precise definition of the rule that defines the label.

Answer 1

[Cedric]

the cyclist >> I knew I had overlooked something easier. :-)

Well, look at how I did overlook something easier ;-D :

 C = {[];[];[];[];[];[];[];[];'rj';'rj';'rj';'ab';'ab'} ;

 setMatch  = @(s,c) struct('string', s, 'count', c) ;
 match     = setMatch('', 0) ;
 hashtable = java.util.Hashtable() ;

 for k = 1 : length(C)
     if isempty(C{k}), continue ;  end
     if hashtable.containsKey(C{k})
         count = hashtable.get(C{k}) ;
         if count >= match.count,  match = setMatch(C{k}, count+1) ;  end
         hashtable.put(C{k}, count+1) ; 
     else
         if match.count == 0,  match = setMatch(C{k}, 1) ;  end
         hashtable.put(C{k}, 1) ; 
     end
 end

Running this leads to;

 >> match
 match = 
    string: 'rj'
     count: 3

[Cedric]

Effess: I voted for the answer given by The Cyclist, because it is better. You can update it a little if you want to get rid of the empty cells, as follows: replace

 cellData(indexToEmpty) = {''};

with

 cellData(indexToEmpty) = [];

[DuckDuck]

supposed i have a matrix with these columns, how do i get another matrix with the results match for each column in separate column of match

[Cedric]

If C is a "2D" cell array, yo can get column e.g. 4 as follows:

 C_col = C(:,4) ;

The simplest way to apply either solution (The Cyclist or mine) to all columns is to loop over columns of your cell array, and to save the result in another cell array e.g.

 matches = cell(1, size(C, 2)) ;
 for c = 1 : size(C, 2)
    C_col = C(:,c) ;

    % .. whichever method, applied to C_col ..

    matches{c} = .. the solution, e.g. match.string
 end

[DuckDuck]

i did it but i'm geting an error when trying to save results from columns with more than one string!!

for k=1:length(tsf)
cellData = labelw(:,tsf(k));
indexToEmpty = cellfun(@isempty,cellData);
cellData(indexToEmpty) = [];
[uniqueCellData(:,k),~,whichCell] = unique(cellData);
end;

[Cedric]

You don't need to save the content of temporary variables at each iteration of the loop. You just need to save results, and you should have something like (where the ".." have to be adapted to your case):

 maxCountElements = cell(size(..), 1) ;

 for k = 1 : ..
    cellData = ..
    indexToEmpty = cellfun(@isempty,cellData);
    cellData(indexToEmpty) = [];
    uniqueCellData = unique(cellData);
    [uniqueCellData,~,whichCell] = unique(cellData);
    cellCount = hist(whichCell,unique(whichCell));
    [~,indexToMaxCellCount] = max(cellCount);
    maxCountElements{k} = uniqueCellData(indexToMaxCellCount) ;
 end

Answer 2

[the cyclist]

Quite convoluted, but I think this works:

cellData = {[];[];[];[];[];[];[];[];'rj';'rj';'rj';'rj';'rj';'rj';'rj';'rj';'rj';'rj';'rj';'rj';'rj';'rj';}

indexToEmpty = cellfun(@isempty,cellData);
cellData(indexToEmpty) = {''};

uniqueCellData = unique(cellData);

[~,whichCell] = ismember(cellData,unique(uniqueCellData))

cellCount = hist(whichCell,unique(whichCell));

[~,indexToMaxCellCount] = max(cellCount);

maxCountElement = uniqueCellData(indexToMaxCellCount)

The essence of the algorithm is using the hist() function to count up the frequency. Unfortunately, that function only works on numeric arrays, so I had to use the ismember() command to map the cell array values to numeric values.

A further complication was the existence of the empty cell elements. I replaced them with empty strings. You'll need to be careful if your original array has empty strings.

[DuckDuck]

maybe i did ask the question wrong, but if i have more {''} it will give me that name. instead i want {'rj'}. is there a workaround to counting?

[Matt J]

No need for ismember,

[uniqueCellData,~,whichCell] = unique(cellData);

[the cyclist]

I knew I had overlooked something easier. :-)

Answer 3

[Peter Saxon]

Found a neat solution with categories, just posting this here so when I forget how to do this and google it again I'll see it...

C = {[];[];[];[];[];[];[];[];'rj';'rj';'rj';'ab';'ab'} ;

catC=categorical(C);
catNames=categories(catC);
[~,ix] = max(countcats(catC));

disp(catName{ix}) % rj