MATLAB: How to use ismember in a cell array

cell arraysindexingismemberloops are fast

I would like to change the value of some value within a cell array that has only numeric data, preferably not using loops because I will be performing this operation with large cell arrays many times.
    % Given:
    A = {[1 2 3] [3 4 5 6];[7 8] [9 1 2 3 4];[5] [6 7 8 9]};
    B = 1;
    % Set all values in A equal to B as NaN.
    % If A were a double then it would look like this:
    A(ismember(A,B)) = NaN;
I've been trying to use this
    A(cellfun(@(x) x == B(1),A,'un',0))
But I get this error:
"Function 'subsindex' is not defined for values of class 'cell'."

Best Answer

Try it with loops, because there is no general rule that loops are slow:
A = {[1 2 3] [3 4 5 6];[7 8] [9 1 2 3 4];[5] [6 7 8 9]};
B = 1;
for iA = 1:numel(A)
  tmpA  = A{iA};
  tmpA(tmpA == B) = NaN;
  A{iA} = tmpA;
end
Measure the timings using timeit or tic/toc. cellfun with anonymous function is not really fast also, because handling the anonymos function for each element needs some time, perhaps more than the loop overhead.
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