How delete duplicate strings in cell array

I have a matrix with some cell arrays of chars representing numbers and I need to eliminate duplicate elements of each columns. I tried using unique but when I have elements with diferents lengths unique do not solve the problem.

My data is :

M= {'100'  '500'  '2  3  4'  '50000'; '100' '500' '2' '0';'100' '500' '3' '0';'100' '500' '4' '0';'100' '500' '2  3  4' '20000'};

M = 5x4 cell of chars

unique(M(:,1)) %gives me  '100'
unique(M(:,2)) %gives me '500'

both are corrects but

unique(M(:,3)) %gives me  '2' '2  3  4' '3' '4'
unique(M(:,4)) %gives me '0' '0 20000' '20000' '50000'

and I need only one result: '2 3 4' for column 3 and '0 20000 50000' for column 4

Matrix M is size N x 4

The result I need is R = {'100' '500' '2 3 4' '0 20000 50000' }

My code is strange and I need a more nice solution, I am using Matlab version 2017b.

 for i=1:4   
    mm = M(:,i);  
    tmp=unique(mm);
    if size(tmp,1) == 1
        R{i} = char(tmp);
    else
        R{i}=char(cellstr(strjoin(unique(split(string(strjoin(mm,' ')))))));
    end
 end

Answer 1

[Stephen23]

You could easily hide the loop inside cellfun, e.g.:

>> fun = @(c)sprintf(' %u',unique(sscanf(sprintf(' %s',c{:}),'%f')));
>> out = cellfun(fun,num2cell(M,1),'uni',0)
out = 
    ' 100'    ' 500'    ' 2 3 4'    ' 0 20000 50000'

Of course with R2017b you can probably replace the outer sprintf with strjoin.

[Marcelo]

It works, but how to replace fun with strjoin?

[Stephen23]

"but how to replace fun with strjoin?"

I don't think that it is possible to replace the entire function with one strjoin call.

But you might be able to replace the outer sprintf with strjoin, as I wrote. Try it.