How can I compare strings and create a new column with the comparison result?

I have "cat1" and "cat2" that are 2 columns with strings:

If cat1 is low and cat2 is low, I want cat3 to be '1'; If cat1 is medium low and cat2 is medium low, I want cat3 to be '2'; And so on until high and high. If none of these conditions are satisfied, I want cat3 to be '0';

How can I do this? I tried this way but it says "Undefined operator '==' for input arguments of type 'cell'" :

teste1 = repmat( {''}, length(catpreco(:,1)), 1);
mask = catpreco(:,1) == 'low' & catconsumo(:,1)== 'low';
catpreco(mask) = cellfun(@(S) [S, '1'], catpreco(mask), 'Uniform', 0);
mask = catpreco(:,1) == 'medium low' & catconsumo(:,1)== 'medium low';
catpreco(mask) = cellfun(@(S) [S, '2'], catpreco(mask), 'Uniform', 0);
mask = catpreco(:,1) == 'medium' & catconsumo(:,1)== 'medium';
catpreco(mask) = cellfun(@(S) [S, '3'], catpreco(mask), 'Uniform', 0);
mask = catpreco(:,1) == 'medium high' & catconsumo(:,1)== 'medium high';
catpreco(mask) = cellfun(@(S) [S, '4'], catpreco(mask), 'Uniform', 0);
mask = catpreco(:,1) == 'high' & catconsumo(:,1)== 'high';
catpreco(mask) = cellfun(@(S) [S, '5'], catpreco(mask), 'Uniform', 0);

[Jan]

I've formatted the code. Please use the "{} code" button to provide readable code. Thanks.

Answer 1

[Jan]

The error message means, that you cannot compare a cell array with a string using the == operator. Use strcmp instead:

cat3    = cell(size(cat1));
cat3(:) = {'0'};

mask       = strcmp(cat1, 'low') & strcmp(cat2, 'low');
cat3(mask) = {'1'};
mask       = strcmp(cat1, 'medium low') & strcmp(cat2, 'medium low');
cat3(mask) = {'2'};
mask       = strcmp(cat1, 'medium') & strcmp(cat2, 'medium');
cat3(mask) = {'3'};
mask       = strcmp(cat1, 'medium high') & strcmp(cat2, 'medium high');
cat3(mask) = {'4'};
mask       = strcmp(cat1, 'high') & strcmp(cat2, 'high');
cat3(mask) = {'5'};

A loop might be nicer:

list = {'low', 'medium low', 'medium', 'medium high', 'high'};
for k = 1:5
  mask       = strcmp(cat1, list{k}) & strcmp(cat2, list{k}));
  cat3(mask) = {sprintf('%d', k)};
end

[Guillaume]

Even simpler (no loop):

 list = {'low', 'medium low', 'medium', 'medium high', 'high'};
 cat3 = zeros(size(cat1));
 [~, cat1result] = ismember(cat1, list);
 [~, cat2result] = ismember(cat2, list);
 cat3(cat1result == cat2result) = cat1result(cat1result == cat2result);

[Eduardo Rocha]

Thank you, now its easier to understand and the code works perfectly :)