Hi Rui, Thank you very much for your help!! It works very well, I got it.
Ding -----Original Message----- From: Rui Barradas [mailto:ruipbarra...@sapo.pt] Sent: Thursday, April 19, 2018 11:35 AM To: Ding, Yuan Chun <ycd...@coh.org>; r-help@r-project.org Subject: Re: [R] create multiple categorical variables in a data frame using a loop [Attention: This email came from an external source. Do not open attachments or click on links from unknown senders or unexpected emails.] Hello, When programming it is better to use dat[["variable"]] than dat$variable. So your code could be pfas.pheno[[cat.var]] <- NA pfas.pheno[[cat.var]][pfas.pheno[,i] <= quantile(pfas.pheno[,i],0.25, na.rm =T)] <- 0 etc. Untested. Hope this helps, Rui Barradas On 4/19/2018 7:20 PM, Ding, Yuan Chun wrote: > Hi All, > > I want to create a categorical variable, cat.pfoa, in the file of pfas.pheno > (a data frame) based on log2pfoa values. I can do it using the following code. > > pfas.pheno <-within(pfas.pheno, {cat.pfoa<-NA > cat.pfoa[pfas.pheno$log2pfoa <=quantile(pfas.pheno$log2pfoa,0.25, na.rm > =T)]<-0 > cat.pfoa[pfas.pheno$log2pfoa >=quantile(pfas.pheno$log2pfoa,0.75, na.rm > =T)]<-2 > cat.pfoa[pfas.pheno$log2pfoa >=quantile(pfas.pheno$log2pfoa,0.25, na.rm =T) > &pfas.pheno$log2pfoa <=quantile(pfas.pheno$log2pfoa,0.75, na.rm > =T)]<-1 > } > > However, I have additional 7 similar variables, so I wrote the following > code, but it does not work. > > for (i in c("log2pfoa","log2pfos", "log2pfna", "log2pfdea", "log2pfuda", > "log2pfhxs", "log2et_pfosa_acoh", "log2me_pfosa_acoh")) { > cat.var <- paste0("cat.",i) > pfas.pheno <- within(pfas.pheno, {eval(parse(text= cat.var))<-NA > eval(parse(text=cat.var))[pfas.pheno[,i] <= > quantile(pfas.pheno[,i],0.25, na.rm =T)] <- 0 > eval(parse(text=cat.var))[pfas.pheno[,i] >= quantile(pfas.pheno[,i],0.75, > na.rm =T)] <- 2 eval(parse(text=cat.var))[pfas.pheno[,i] >= > quantile(pfas.pheno[,i],0.25, na.rm =T) > &pfas.pheno[,i] <= > quantile(pfas.pheno[,i],0.75, na.rm =T)] < -1 > }) > > > } > > Can you help me fix the problem? > > Thank you, > > Yuan Chun Ding > City of Hope National Medical Center > > > > --------------------------------------------------------------------- > -SECURITY/CONFIDENTIALITY WARNING- > This message (and any attachments) are intended solely > f...{{dropped:22}} > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
