How to transform 'double' into 'cell array'?

Question

My code:

B = zeros(height(A),1);
col_names = A.Properties.VariableNames; % Replicate header names 
for k = 1:height(A)
    % the following 'cellfun' compares each column to the values in A.L{k},
    % and returns a cell array of the result for each of them, then
    % 'cell2mat' converts it to logical array, and 'any' combines the
    % results for all elements in A.L{k} to one logical vector:
    C = any(cell2mat(...
        cellfun(@(x) strcmp(col_names,x),A.L{k},...
        'UniformOutput', false).'),1);
    % then a logical indexing is used to define the columns for summation:
    B(k) = sum(A{k,C});
end

generates the following error message.

Error using cellfun
Input #2 expected to be a cell array, was double instead.

How do I solve this error?

This is how table 'A' looks like:

A.L{1,1} contains:

Answer 1

I'm not entirely sure quite what's going on here, but here's a fabricated example that I think is similar to what you're trying to achieve.

%% Setup - fabricate some data
colNames = {'xx', 'yy', 'zz', 'qq'};
h = 20;
% It looks like 'L' contains something related to the column names
% so I'm going to build something like that.
L = repmat(colNames, h, 1);
% Empty some rows out completely
L(rand(h,1) > 0.7, :) = {''};
% Empty some other cells out at random
L(rand(numel(L), 1) > 0.8) = {''};
A = table(L, rand(h,1), rand(h, 1), rand(h, 1), rand(h, 1), ...
    'VariableNames', ['L', colNames]);

%% Attempt to process each row
varNames = A.Properties.VariableNames;
B = zeros(height(A), 1);
for k = 1:height(A)
    % I think this is what's required - work out which columns are
    % named in "A.L(k,:)". This can be done simply by using ISMEMBER
    % on the row of A.L.
    C = ismember(varNames, A.L(k,:));
    B(k) = sum(A{k, C});
end

If I'm completely off-course here, then perhaps you could give us an executable example.

Answer 2

C = any(cell2mat(...
    cellfun(@(x) strcmp(col_names,x),A.L{k},...
    'UniformOutput', false).'),1);

here A.L{k} gets the contents of the cell located at the kth position of A.L. Using A.L(k) you get the cell itself which is located at A.L:

tmp = A.L(k);
C = any(cell2mat(...
    cellfun(@(x) strcmp(col_names,x),tmp{1},...
    'UniformOutput', false).'),1);

Bit of a hacky way, as you first need to get the cell at A.L(k) and then need the contents of that cell, so you need a temporary variable.