cat is a data.frame, so cbind is use for a data.frame
and ?data.frame tell us that:
Character variables passed to 'data.frame' are converted
to factor columns unless protected by 'I'.PS : it is not good ides to call your data.frame cat as there is a cat function.
At 09:19 10/12/2004, michael watson (IAH-C) wrote:
Hi
I'm seeing some "odd" behaviour with cbind(). My code is:
> cat <- read.table("cogs_category.txt", sep="\t", header=TRUE, quote=NULL, colClasses="character") > colnames(cat) [1] "Code" "Description" > is.factor(cat$Code) [1] FALSE > is.factor(cat$Description) [1] FALSE > is.factor(rainbow(nrow(cat))) [1] FALSE > cat <- cbind(cat,"Color"=rainbow(nrow(cat))) > is.factor(cat$Color) [1] TRUE > ?cbind
I read a text file in which has two columns, Code and Description. Neither of these are factors. I want to add a column of colours to the data frame using rainbow(). The rainbow function also does not return a factor. However, if I cbind my data frame (which has no factors in it) and the results of rainbow() (which is a vector, not a factor), then for some reason the new column is a factor...??
Mick
Michael Watson Head of Informatics Institute for Animal Health, Compton Laboratory, Compton, Newbury, Berkshire RG20 7NN UK
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