how to extend a cell array?

i have a 1D cell array . i wish to increase its size by adding zeros to its right . i think i can use pad array with LOC as 'b' but i dont know the synax. help me with this please.

Answer 1

[Image Analyst]

Try this:

ca{1} = 'abc' % Put string in first cell.
% Now pad with cells that have a numerical zero in them.
for k = 2 : 15
    ca{k} = 0;
end

[Nabhdeep Bansal]

thank you sir

[Stephen23]

No preallocation and a slow loop, this is a poor solution as the cell array gets expanded and MATLAB has to keep reallocating memory... see my answer for a faster and neater solution.

[Image Analyst]

Yes, your way is faster and more "MATLAB-ish" which is why I voted for it. Though for only 15 cells you won't notice. My method took only 40 microseconds:

Elapsed time is 0.000040 seconds.

With a million elements to set it gets almost up to a second while your method stays short (around 15 microseconds).

[Stephen23]

Of course for small arrays it will not make much difference... but surely it is just as easy to learn good habits rather than to have to unlearn bad ones?

After all today's undergrad is tomorrows PhD candidate, and then it really will make a difference to their muon-path dataset analysis.

Thank you for the vote!

Answer 2

[Stephen23]

A fast and neat way to do this would be to use basic MATLAB indexing and scalar expansion:

>> ca{1} = 'abc'
>> ca(2:15) = {0}; % put whatever value you want in this scalar cell

Just one line of code and no loops are required to extend a cell array. Note that that curly brackets and parentheses are deliberate!

Answer 3

[Thorsten]

Sample cell

 C{1} = 100;
 C{2} = rand(2);
 C{3} = 'a';

% add zeros up to cell 23

 C{23} = 0;

 z0{1} = 0;
 C(logical(cellfun(@isempty, C))) = deal(z0);

[Thorsten]

See Stephen's answer for the easy and better way to do it...