coding variable values into classes using R

Question

I have a set of data in which I need to code values of certain variables (numeric) into 3 classes.

My data set is similar to this but has 60 more variables:

Answer 1

Just to show an alternate (similar to recode in SPSS) method from package car:

> data$SWT <- with(data, recode(wt, "lo:200=1; 300:hi=3; else=2"))
> data
   anim    wt SWT
1     1 181.0   1
2     2 179.0   1
3     3 180.5   1
4     4 201.0   2
5     5 201.5   2
6     6 245.0   2
7     7 246.4   2
8     8 189.3   1
9     9 301.0   3
10   10 354.0   3
11   11 369.0   3
12   12 205.0   2
13   13 199.0   1
14   14 394.0   3
15   15 231.3   2