Checking dimensions of a factor variable in R

Question

This is a short question, but how do I look up the dimensions of a factor variable in R? I tried:

dim(X)
nrow(X)
ncol(X)

but all return NULL

You should reassign the word "dimensions" in your R-brain convolutions or gyri to describe `matrices` and `data.frames`. In R these are NOT "dimensions". — IRTFM, Feb 07 '13 at 04:30

mnel · Accepted Answer · 2013-02-07T02:06:28.157

6

If we have an atomic variable (which a factor is), it will have a length value

X <- factor(letters)

length(X)

## [1] 26

It will also have levels

levels(x)

When X is a factor, it is the following classes

is(X)
[1] "factor"   "integer"  "oldClass" "numeric"  "vector"

edited Feb 07 '13 at 02:06

answered Feb 07 '13 at 01:22

mnel

score 1 · Answer 2 · answered Feb 11 '13 at 19:12

1

Also the str() function is helpful when one has a dataframe and needs to get an idea of many different levels at once.

answered Feb 11 '13 at 19:12

Jack Ryan

2 Answers2