Finding row indices of a cell array containing a certain element

I hae the following cell array.

arr = cell(4,1);

arr{1,1}=1:3:15;
arr{2,1}=2:2:20;
arr{3,1}=3:3:30;
arr{4,1}=0:4:10;

%% I need to find the row indices of cells containing the element '4', i.e., the output should be

% k = [1;2;4]

Answer 1

[Rik]

A simple loop should do:

arr = cell(4,1);
arr{1,1}=1:3:15;
arr{2,1}=2:2:20;
arr{3,1}=3:3:30;
arr{4,1}=0:4:10;

L=false(numel(arr),1);
for n=1:numel(arr)
    L(n)=ismember(4,arr{n});
end
k=find(L)

k = 3×1

1 2 4