R help - Jan 1999 - character vectors in data.frames

Dear all,

well, today I just seem to run into these problems ... (I am still working
on R 0.63.1 on a SuSE 5.2). I would like to have a data.frame that also
contains character (and NOT factor) vectors. Two things that I tried (the
second worked in R 0.62.2):
> test.df <- data.frame (X= character (4))
> test.df$X [1] <- "a"
Warning: invalid factor level, NAs generated

or:
> X <- c ("a", "b", "c")
> is.character (X)
[1] TRUE
> test.df <- data.frame (X)
> is.character (test.df$X)
[1] FALSE

Any suggestions how to achieve this? Many thanks!

--			~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Lorenz Gygax		 LGygax at amath.unizh.ch;       room: 36-L-40
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Lorenz Gygax <lgygax at access.unizh.ch> writes:
> Dear all,
> 
> well, today I just seem to run into these problems ... (I am still working
> on R 0.63.1 on a SuSE 5.2). I would like to have a data.frame that also
> contains character (and NOT factor) vectors. Two things that I tried (the
> second worked in R 0.62.2):
> 
> > test.df <- data.frame (X= character (4))
> > test.df$X [1] <- "a"
> Warning: invalid factor level, NAs generated
> 
Use I(). Like this:
> test.df <- data.frame (X= I(character (4)))
>  test.df$X [1] <- "a"
> test.df
  X
1 a
2  
3  
4  
> test.df$X
[1] "a" ""  ""  "" 
attr(,"class")
[1] "AsIs"

And yes, the behaviour that data.frame converts character to factor
unless requested otherwise is weird, but Splus compatible.

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
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r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
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