Dennis Fisher [EMAIL PROTECTED] writes:
Colleages
I am running R 2.1.0 on a Mac (same problem occurs in Linux). In
some situations, I have mixed text/numeric data that is stored as
characters in a matrix. If I convert this matrix to a dataframe, the
numeric data becomes factors, not what I intend.
TEXT- paste(Text, 1:4, sep=)
NUMBERS- 10 + 4:1
MATRIX- cbind(TEXT, NUMBERS)
FRAME- as.data.frame(MATRIX)
str(FRAME)
`data.frame':4 obs. of 2 variables:
$ TEXT : Factor w/ 4 levels Text1,Text2,..: 1 2 3 4
$ NUMBERS: Factor w/ 4 levels 11,12,13,..: 4 3 2 1
One work-around is to write the matrix (or the dataframe) to a file,
then read the file back using the as.is argument.
write.table(MATRIX, JUNK, row.names=F)
NEWFRAME- read.table(JUNK, as.is=T, header=T)
str(NEWFRAME)
`data.frame':4 obs. of 2 variables:
$ TEXT : chr Text1 Text2 Text3 Text4
$ NUMBERS: int 14 13 12 11
This restores the NUMBERS to their intended mode (integers, not
factors). The text column is also not read as a factor (not a
problem for me).
It appears that the function AsIs [I(x)] would enable me to
accomplish this without the write/read steps. However, it is not
obvious to me how to implement I(x). Can anyone advise?
I don't think that is going to help
There are really several issues here: Your numeric column was
converted to character by the cbind, using as.data.frame(I(MATRIX))
will not split it into individual columns, and things like
apply(MATRIX,2,f) may do the right thing to begin with, but then
there's coercion due to an implicit cbind at the end.
It's a bit awkward, but this may do it:
FRAME - as.data.frame(lapply(split(MATRIX,col(MATRIX)),type.convert))
names(FRAME) - colnames(MATRIX)
str(FRAME)
`data.frame': 4 obs. of 2 variables:
$ TEXT : Factor w/ 4 levels Text1,Text2,..: 1 2 3 4
$ NUMBERS: int 14 13 12 11
whereas this isn't right:
str(apply(MATRIX,2,type.convert))
int [1:4, 1:2] 1 2 3 4 14 13 12 11
- attr(*, dimnames)=List of 2
..$ : NULL
..$ : chr [1:2] TEXT NUMBERS
--
O__ Peter Dalgaard Øster Farimagsgade 5, Entr.B
c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907
__
R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
