how to compute histogram on non-numeric data set?

[Richard]

I have noticed histogram_numeric(col, n), but it seems to require numeric 
column.
I have a string column, they are numeric like string but are category label, 
e.g,
 
100001, 200034
 
two different strings are two different category but the numeric value does not 
mean anything,
so it is not proper to use histogram_numeric(cast(col to BIGINT), n).
 
thanks.
Richard