Gary Collins
2001-Apr-05 09:05 UTC
[R] factors and characters when attaching data...more info.
R-helpers... Please find an ammendment to a problem I posted yesterday (04/04/01). Unfortunately I recieved only one response, so I will give some more details to the problem. I have read some data called Version3.Studies, and to make life slightly easier and programming less wordy, I want to attach a dataframe, but when I do, all of my charater fields are forced into factors.> Version3.Studies_read.table("c:\\Version3.Studies.dat",header=TRUE,as.is=TRUE, strip.white=TRUE)> summary(Version3.Studies$Group)Length Mode 3103 character> is.character(Version3.Studies$Group) # Just to make sure...[1] TRUE> unique(Version3.Studies$Group)[1] "Lung" "Mesothelioma" "Breast" "HeadandNeck" "Oesophagus" [6] "Ovary" "Brain" "Prostate" "Testes" "Stomach" [11] "ColonRectum">Now I attach the data...> attach(Version3.Studies) > is.character(Group)[1] FALSE> is.factor(Group)[1] TRUE>> unique(Group)[1] Lung Mesothelioma Breast HeadandNeck Oesophagus [6] Ovary Brain Prostate Testes Stomach [11] ColonRectum Levels: Lung Brain Ovary Breast Testes Stomach Prostate Oesophagus ColonRectum HeadandNeck Mesothelioma Now, consider the following simple example, I want to extract another field, say PF in Version3.Studies but indexing by a label in Group, say Lung. Without attaching the data, I can simply do> Version3.Studies$PF[Version3.Studies$Group=="Lung"]and this calls the apropriate data. After attaching the data, to retrieve the same data, I need to do> PF[Group==" Lung"]inserting the neccesary white space. What my question is why is R forcing my character fields to factor when attaching a dataframe, is this what is supposed to happen, and is there a way around it, keeping my original character fields as character and not as factor. Trying to force the Group to a character field still keeps white space which was created when attaching the dataframe.> unique(as.character(Group))[1] " Lung" "Mesothelioma" " Breast" " HeadandNeck" " Oesophagus" [6] " Ovary" " Brain" " Prostate" " Testes" " Stomach" [11] " ColonRectum">Any help would be greatly appreciated. Gary Collins. __________________________________________________ Dr. Gary S. Collins, Statistics Research Fellow, Quality of Life Unit, European Organisation for Research and Treatment of Cancer, EORTC Data Center, Avenue E. Mounier 83, bte. 11, B-1200 Brussels, Belgium. Tel: +32 2 774 1 606 Fax: +32 2 779 4 568 Email: gco at eortc.be http://www.eortc.be/home/qol/ __________________________________________________ -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._