Data as a "matrix", a "data.frame"
or even a "vector" or "factor".
"vector" or "factor" are coerced to a
"data.frame" with one column.
catgories
optional a vector ("numeric" or
"character") containig the categories to tabulate.
At default (catgories=NULL) the fuction looks for
unique categories in X.
na.omit
logical (default: na.omit=FALSE )
wether to return frequencies for missing values,
NAs.
Value
a "matrix" with category frequencies
Details
X can either be a ("numeric" or
"character") "matrix" containing response
vectors of persons (rows) or a "data.frame"
containing "numeric", "character" or
"factor" variables (columns).