how can I filter the nth character from categorical?

i have a categorical value a, looks like:

 a = 888-2018-02160001

Now I want the 10th and 11th character, the '02'.

I already tried a(10:11), but that doesn't work, because the length of a is 1. Also when I try string(a), the length is still 1

How can I filter these characters from a categorical?

Answer 1

[Birdman]

 >>a = '888-2018-02160001'
 a(10:11)

 ans =

     '02'

[Aletta Wilbrink]

I don't create a new variable. I have over 300,000 records with these type of categoricals where I need to do this for

[Birdman]

What does your variable look like? If it is in string form, then simply convert them to char by typing

 char(a)

and then extract 10th and 11th characters at all rows as

a(:,10:11)

[Aletta Wilbrink]

That works, thanks!

Answer 2

[Peter Perkins]

If you have a categorical variable, as in the categorical data type, then it sounds like you want to work with the category names. Converting the entire (large) categorical array will be very inefficient in terms of memory. probably the easiest thing to do is to make a copy, modify the copy's category names using renamecats, and you're done.

Not enough information to go to know if that's what you want.