Converting strcat to use with categoricals

Hi,

We have previously used strings for properties of various entries in tables, and have now converted them to categoricals. Before, we could have cat1 and cat2 and we could create a new merged category by concatenating the two:

tab = table;
tab.cat1 = {'true','false','false','null'}';
tab.cat2 = {'one','one','many','many'}';
tab.cat3 = strcat(tab.cat1, tab.cat2);

Is there a similar approach for categoricals? What we do now is converting back and forth from string, but that seems inefficient and slow for large tables.

tab = table;
tab.cat1 = categorical({'true','false','false','null'}');
tab.cat2 = categorical({'one','one','many','many'}');
tab.cat3 = categorical(strcat(cellstr(tab.cat1), cellstr(tab.cat2)));

Instead it would be nice if you could do something like:

tab.cat3 = catcat(tab.cat1, tab.cat2);

Answer 1

[Peter Perkins]

Andreas, I think the categorical times method is you're looking for:

>> tab = table(categorical({'true','false','false','null'}',{'true' 'false'}), ...
            categorical({'one','one','many','many'}'), ...
            'VariableNames',{'cat1' 'cat2'})
tab = 
       cat1        cat2
    ___________    ____
    true           one 
    false          one 
    false          many
    <undefined>    many
>> tab.cat3 = tab.cat1 .* tab.cat2
tab = 
       cat1        cat2       cat3    
    ___________    ____    ___________
    true           one     true one   
    false          one     false one  
    false          many    false many 
    <undefined>    many    <undefined>

Hope this helps.

[Andreas Brinch Nielsen]

That was exactly what I was looking for. Awesome. Thanks!