How to find values greater than a number in a cell of empty cells?

Hello everyone,

I am trying to find the values greater than '0' in a cell array of few empty cells eg. D = {[],[],[3],[],[],[]}?

I have tried multiple options like

1. find(D{:}>=0)
2. [row,col] = cellfun(@(c) find(c >= 0), D, 'uniform', false)
3. for i = 1 : length(Match), idx(i) = find(Match{1,i}>=0);end
4. ismember(D,3);

But nothing has worked so far?

All the best,

Thanks

Answer 1

[Adam Danz]

D =  {[],[],3,[], -2, 0, [], 1, 6, []};
idx = cellfun(@(x)~isempty(x) && x >= 0, D); % logical index

If you need the subscript index,

idx = find(cellfun(@(x)~isempty(x) && x >= 0, D)); % subscript index

If D contains non-scalars,

D =  {[],[],3,[], -2, 0, [], 1, 6, [], -2:2, magic(4)-8};
idx = cellfun(@(x)~isempty(x) & x >= 0, D, 'UniformOutput', false);

but now idx is a cell-array so to find the values >= 0 in element n of D, idx{n}.

[BR]

Thanks Adam, big relief. I understood the concept too.

[BR]

Hi Adam, once again, I have been trying to solve a problem (the reason for which I asked the above question) for merging a double and a cell array as cell in a way that the continuity of the values is maintained.

Say, A = [1,2,6,10,21];

B = {[3;4;5],[7;8;9],[11,12...20]};

I have to merge these two such that

C = {[1],[2],[3;4;5],[6],[7;8;9],[10],[11,12...20],[21]}

please help and thanks

[Adam Danz]

A = [1,2,6,10,21];
B = {[3;4;5],[7;8;9],[11,12:20]};

% Convert A to a cell array and horizontally 
% contatenate A and B 
C = [B, num2cell(A)]; 

% Sort C based on 1st value within each cell element
[~, sortIdx] = sort(cellfun(@(x)x(1),C)); 
C = C(sortIdx); 

[BR]

Thanks Adam, I got this error message,

Index exceeds the number of array elements (0).

Error in @(x)x(1)

May be because I did this mistake while explaining ,

B = {[3;4;5],[7;8;9],[11;12;13;14;.....20]};

Thanks

[Adam Danz]

It looks like one of your cell elements is empty. What's supposed to happen with empty cells during the sort? Should they be removed?

[BR]

Hey,

Ohh yes you're right. One of the cell element is empty. How did you know that?

Yes they are supposed to be removed.

Thanks

[Adam Danz]

If you get an error trying to index the first value in a cell array element, that means there's nothing in that cell element.

Add this line before the sort() line

% Remove empties
C(cellfun(@isempty,C)) = []; 

[BR]

Thanks mate, ohh so it can be in any cell array element not necessarily the first cell. I thought it is giving an error in the first cell.

cheers mate.

[Adam Danz]

This line sort(cellfun(@(x)x(1),C)) merely extracts the first value within each element of the cell array C. The elements of C can be scalar, vectors (rows or columns), matricies, multi-dim arrays, any numeric format. But when in comes across an empty element it throws an error because there is no first-value to extract.

[BR]

Ok, thanks man. Appreciate it and sorry for the late response.