Arrange string based on 1 or 0 value

Hi. I have question regarding to cell string and matrix. I have matrix F and cell string D. I want to create another cell string Y.

F =

0 0 0 0 
1 0 0 1
0 1 1 1
1 1 1 1

D =

    'A'
    'B'
    'C'
    'D'

Therefore, I want to create Y with output like this.

Y =

    '-'
    'A, D'
    'B, C, D'
    'A, B, C, D'

The steps are:

-1- recognize column positions of value 1 for row 1 in F.

-2- the column positions are equal to row positions of D. So, string in that row positions will input to row 1 of Y.

-3- do the same step for next row in F and D. If no value 1 for that row, that row position of Y will be empty, and maybe can be replace with sign - as to indicate no string available from D.

Answer 1

[Stephen23]

[col,row] = find(F');
fun = @(v){sprintf(', %s',D{v})};
out = accumarray(row,col,[],fun);
out = cellfun(@(s)s(3:end),out,'uni',0)
out(cellfun('isempty',out)) = {'-'};

giving:

>> out{:}
ans = -
ans = A, D
ans = B, C, D
ans = A, B, C, D

[Guillaume]

fun = @(v) {strjoin(D(v), ', ')};

would be a lot simpler since you then don't need the cellfun to remove that leading ', ' inserted by sprintf:

[col,row] = find(F');
fun = @(v) {strjoin(D(v), ', ')};
out = accumarray(row,col,[],fun);
out(cellfun('isempty',out)) = {'-'};

[Stephen23]

@Guillaume: agreed... but sadly not on the MATLAB version I have.

[Guillaume]

It's trivial to implement:

function s = strjoin(strings, joint)
    join = cell(2, numel(strings));
    join(1, :) = strings(:);
    join(2, 1:end - 1) = {joint};
    s = [join{:}];
end

Answer 2

[KSSV]

F =[0 0 0 0 
1 0 0 1
0 1 1 1
1 1 1 1] ;

D = {'A' 'B' 'C' 'D'} ;

F = logical(F) ;

for i = 1:4
    iwant = D(F(i,:)) 
end

[Jan]

Note: Changing the type of a variable can degrade the processing speed, because the JIT acceleration is impeded. Something like LF=logical(F) is a very cheap way to increase the speed.

[yue ishida]

The final iwant is not similar with Y. The output is like this

iwant =

   Empty cell array: 1-by-0

iwant =

    'A'    'D'

iwant =

    'B'    'C'    'D'

iwant =

    'A'    'B'    'C'    'D'

so final is ABCD in one row, not 4 rows, unlike Y. Can you help me find the right one?