Combining cell arrays with empty doubles

Suppose I have two cell arrays, with

a = cell(1,2);
a{1} = 1;
b = cell(1,2);
b{2} = 2;

How can I quickly combine the two to give me

1×2 cell array

    {[1]}    {[2]}
    

?

In general, I want to combine several cell arrays of the same dimension, which at a given index either either all have {0×0 double} doubles or at most one of the cell arrays does not have a {0×0 double} double.

Thanks!

Michael

Answer 1

[Stephen23]

% slightly more complex example data:
a = {[],1;[],[]};
b = {[],[];2,[]};
c = {[],[];[],NaN};
%
tmp = cat(3,a,b,c);
[~,idp] = sort(cellfun('isempty',tmp),3);
sz = size(tmp);
[idr,idc] = ndgrid(1:sz(1),1:sz(2));
idx = sub2ind(sz,idr,idc,idp(:,:,1));
out = tmp(idx)

out = 2x2 cell array
    {0×0 double}    {[  1]}
    {[       2]}    {[NaN]}

Answer 2

[Jan]

Or simpler:

a = {1, []};
b = {[], 2};

c = cat(2, a, b);
c = c(~cellfun('isempty', c));

% Or:
fullCell = @(x) x(~cellfun('isempty', x));
c = cat(2, fullCell(a), fullCell(b));