[R] character vectors in data.frames

[Peter Dalgaard BSA]

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   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907
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