Get the number of levels of a categorical variable as a single number in Stata -

i trying find way number of levels of categorical variable single number. example if have variable x 4 levels need somehow number. if type levelsof x following 1 2 3 4 can't number 4 there. there way using levelsof or command?

various commands give number of distinct values, kind of variable. ("categorical variable" statistical concept, rather stata concept.) perhaps simplest way one-off purposes ask one-way tabulation using tabulate. number of distinct values number of rows in table, returned r(r). note (1) can suppress table (which useful in program or file) , (2) missing values excluded default:

. sysuse auto, clear (1978 automobile data)  . qui tab foreign  . ret li  scalars:                   r(n) =  74                   r(r) =  2  . qui tab rep78  . ret li  scalars:                   r(n) =  69                   r(r) =  5  . qui tab rep78, missing  . ret li  scalars:                   r(n) =  74                   r(r) =  6 

an extended review of problem, pitched more generally, available here. paper introduces distinct command. uses include direct support looking @ number of distinct values systematically. search distinct in stata find download source recent version.

. distinct                |           observations               |         total      distinct --------------+----------------------------          make |            74            74         price |            74            74           mpg |            74            21         rep78 |            69             5      headroom |            74             8         trunk |            74            18        weight |            74            64        length |            74            47          turn |            74            18  displacement |            74            31    gear_ratio |            74            36       foreign |            74             2