R help - Apr 2006 - factor levels on import

I have a data frame that I plan on importing from a file (there are 
other columns of numeric data):
 > xy
  x y
1 1 1
2 1 1
3 1 1
4 1 1
5 2 2
6 2 2
7 2 2
8 2 2
 >

where x is a column of factors, and y is a column of factors, that have 
different levels, e.g.,
 > x
[1] low low low low hi  hi  hi  hi
Levels: low hi
 > y
[1] med   med   med   med   medhi medhi medhi medhi
Levels: med medhi

How do I get the columns to use the combined levels  
c("low","med","medhi","high") so that
the data frame is actually:
 > xy
  x y
1 1 2
2 1 2
3 1 2
4 1 2
5 4 3
6 4 3
7 4 3
8 4 3
 >

I'm sure there's a way to lapply or some such, but haven't broken
the
code. I'm also sure I'm missing something simple.

thanx
steve


R 2.2.1
Windows XP

Stephen C. Upton wrote:
> I have a data frame that I plan on importing from a file (there are 
> other columns of numeric data):
>  > xy
>   x y
> 1 1 1
> 2 1 1
> 3 1 1
> 4 1 1
> 5 2 2
> 6 2 2
> 7 2 2
> 8 2 2
>  >
> 
> where x is a column of factors, and y is a column of factors, that have 
> different levels, e.g.,
>  > x
> [1] low low low low hi  hi  hi  hi
> Levels: low hi
>  > y
> [1] med   med   med   med   medhi medhi medhi medhi
> Levels: med medhi
> 
> How do I get the columns to use the combined levels  
> c("low","med","medhi","high") so
that the data frame is actually:
>  > xy
>   x y
> 1 1 2
> 2 1 2
> 3 1 2
> 4 1 2
> 5 4 3
> 6 4 3
> 7 4 3
> 8 4 3
>  >
>
1. R treads each factor separately
2. R cannot know the levels, in particular not that you want to shift 
the representation.

=> you have to do the job more or less manually


Uwe Ligges

> I'm sure there's a way to lapply or some such, but haven't
broken the
> code. I'm also sure I'm missing something simple.
> 
> thanx
> steve
> 
> 
> R 2.2.1
> Windows XP
> 
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