How to determine which indices in a row cell array contains the value 1, even when there are null vectors [ ] in the cell array?

Hello,

If I have a row cell array,

 C = {[], [], [], [], 1, 1, 1, 1, 1, 1, 4, 4, 5, 5, 5, [], [], []}

and I would like to know where in the cell array (i.e. which column) the 1 values are located. How do I grab the indices of where 1 is located because when I use the following,

 d = find([b{:}] == 1)

I get the following output.

 d = [1, 2, 3, 4, 5, 6]

which is not what I want because it ignores the null vector, []...Ideally, I would like the following output, or something like that.

 d = [5, 6, 7, 8, 9, 10]

I'm using MATLAB 2015a btw. Any help or advice would be appreciated. Thanks.

Answer 1

[Walter Roberson]

   find(cellfun(@(x) isequal(x,1), C))

[George Vuong]

Hey Walter, thanks for your response. The output was just what I was looking for. I understand that cellfun applies a function to each cell of a cell array. But can you provide a little explanation as to what @(x) isequal(x,1) does and means?

UPDATE: I think I figured it out. @x creates an anonymous function. And isequal(x,1) inspects each column to see if the value is 1.

Answer 2

[Andrei Bobrov]

C = {[], [], [], [], 1, 1, 1, 1, 1, 1, 4, 4, 5, 5, 5, [], [], []};
b = C;
b(cellfun(@isempty,b))={nan};
d = find([b{:}]==1);

[George Vuong]

Hey Andrei, thank you for your input. It's interesting how in order for

 d = find([b{:}]==1);

to recognize that the null vectors, [], is a column, you have to input nan within [].

Answer 3

[Cedric]

 find( cellfun( @(x) ~isempty(x) && x==1, C ))
 ans =
     5     6     7     8     9    10

[Walter Roberson]

 find(cellfun(@(x) isequal(x,1), C))

[Cedric]

@Walter: I vote for your solution if you post it as an answer!