How to change value in a table so the old one is no longer in the table

Hi everyone, I am trying to replace values in the table pizzasize using code

ind = find(pizzasize.CrustDescription == 'MidCrust');
for i = 1 : size(ind)
    pizzasize.CrustDescription(ind(i)) = 'Mid';
end
ind = find(pizzasize.CrustDescription == 'ClassicCrust');
for i = 1 : size(ind)
    pizzasize.CrustDescription(ind(i)) = 'Mid';
end
ind = find(pizzasize.CrustDescription == 'ThinNCrispy');
for i = 1 : size(ind)
    pizzasize.CrustDescription(ind(i)) = 'Thin';
end
ind = find(pizzasize.CrustDescription == 'ThinCrust');
for i = 1 : size(ind)
    pizzasize.CrustDescription(ind(i)) = 'Thin';
end

but when I call summary(pizzasize) I get

      CrustDescription: 250×1 categorical

          Values:

              ClassicCrust     0                
              DeepPan         83                
              MidCrust         0                
              ThinCrust        0                
              ThinNCrispy      0                
              Mid             85                
              Thin            82

How can I get rid of the values, that are no longer present in the table? Thanks for help.

[Paolo]

You are never actually deleting those values. Try deleting them with:

 pizzasize.MidCrust = [];
 pizzasize.ThinCrust = [];
 pizzasize.ThinNCripsty = [];

[Antonie Brozova]

It returns

Cannot delete 'MidCrust' from the table because it does not exist. Assigning the literal value [] to a
variable in a table deletes the variable. To create a new variable in the table with the value [], use
T.MidCrust = zeros(0) or assign first to a temporary workspace variable.

I need to get rid of them, because when I try to perform anova1 on part of the data, it uses all the groups, not the new ones

[the cyclist]

Can you upload the original pizzasize variable in a MAT file?

[Antonie Brozova]

Its .csv originally, but I suppose it could be possible to make a .mat file

[Antonie Brozova]

Here it is

[Paolo]

@Antonie

Apologies, did not realise you were working with a categorical array.

removecats should achieve what you need.

Before removing DeepPan

 categories(pizzasize.CrustDescription)

    {'ClassicCrust'}
    {'DeepPan'     }
    {'MidCrust'    }
    {'ThinCrust'   }
    {'ThinNCrispy' }

Removing DeepPan

 pizzasize.CrustDescription = removecats(pizzasize.CrustDescription,'DeepPan');

 categories(pizzasize.CrustDescription)

    {'ClassicCrust'}
    {'MidCrust'    }
    {'ThinCrust'   }
    {'ThinNCrispy' }

Does this solve the problem?

[Antonie Brozova]

Yes! It works, thanks a lot :)

[Paolo]

@Antonie You are welcome. I have submitted an answer to the question, please accept it so it will be easily visible to other users having the same question, and for the question to be market as closed.

[Peter Perkins]

Antonie, if I am reading your code correctly, you are combining two categories into one, and renaming the combined category. You want mergecats. It's a one-liner:

pizzasize.CrustDescription = mergecats(pizzasize.CrustDescription,{'MidCrust' 'ClassicCrust'},'Mid')

Also: all those loops were not really necessary. If mergecats didn't exist, you'd want to do this:

pizzasize.CrustDescription(pizzasize.CrustDescription == 'MidCrust') = 'Mid'

without a loop (and without a find, for that matter).

Answer 1

[Paolo]

You can remove categories from categorical arrays using removecats.

View your categories with command:

 categories(pizzasize.CrustDescription)

The categories:

    {'ClassicCrust'}
    {'DeepPan'     }
    {'MidCrust'    }
    {'ThinCrust'   }
    {'ThinNCrispy' }

Remove 'DeepPan' category with the command:

 pizzasize.CrustDescription = removecats(pizzasize.CrustDescription,'DeepPan');

The remaining categories:

 categories(pizzasize.CrustDescription)
    {'ClassicCrust'}
    {'MidCrust'    }
    {'ThinCrust'   }
    {'ThinNCrispy' }