[R] how to edit my R codes into a efficient way

[Xuhong Zhu]

Again, thanks a lot.

Xuhong

On 3/6/07, Petr Klasterecky <klaster at karlin.mff.cuni.cz> wrote:
> Xuhong Zhu napsal(a):
> > Hello, Everyone,
> >
> > I am a student an a new learner of R and I am trying to do my homework
> > in R. I have 10 files need to be read and process seperately. I really
> > want to write the codes into something like "macro" to save the lines
> > instead of repeating 10 times of similar work.
> >
> > The following is part of my codes and I only extracted three lines for
> > each repeating section.
> >
> >
> > data.1 <- read.csv("http://pegasus.cc.ucf.edu/~xsu/CLASS/STA6704/pat1.csv",
> > header = TRUE, sep = ",", quote = "",
> > fill = TRUE);
> > data.2 <- read.csv("http://pegasus.cc.ucf.edu/~xsu/CLASS/STA6704/pat3.csv",
> > header = TRUE, sep = ",", quote = "",
> > fill = TRUE);
> > data.3 <- read.csv("http://pegasus.cc.ucf.edu/~xsu/CLASS/STA6704/pat4.csv",
> > header = TRUE, sep = ",", quote = "",
> > fill = TRUE);
> >
> > baby.1 <- data.frame(cuff=data.1$avg_value,
> > time=seq(1,dim(data.1)[1]), patient=rep(1, dim(data.1)[1]))
> > baby.2 <- data.frame(cuff=data.2$avg_value,
> > time=seq(1,dim(data.2)[1]), patient=rep(3, dim(data.2)[1]))
> > baby.3 <- data.frame(cuff=data.3$avg_value,
> > time=seq(1,dim(data.3)[1]), patient=rep(4, dim(data.3)[1]))
> >
> >
> > I also tried the codes below but it doesn't work.
> >
> > for(n in 1:10){
> > mm <- data.frame(cuff=paste("data",n, sep=".")$avg_value,
> > time=seq(1,dim(paste("data",n, sep="."))[1]),
> > patient=rep(1,paste("data",n, sep="."))[1]))
> > assign(paste("baby",n,sep="."), mm)}
>
> This cannot work since paste() gives you quoted character output while
> functions like data.frame() etc expect a name of some R object.
>
> You can use paste when reading individual csv files:
> for(n in 1:10){
> mydata <- read.csv(file=paste('...STA6704/pat',n,'.csv',sep=""), header
> = TRUE, sep = ",", quote = "", fill = TRUE)
> #
> ... further lines to process mydata ...
> }
>
> A faster way of computing would involve reading the individual files
> into a list of dataframes and using lapply() on that list rather than
> processing the data inside the loop.
>
> Petr
>
> > Xuhong
> >
> --
> Petr Klasterecky
> Dept. of Probability and Statistics
> Charles University in Prague
> Czech Republic
>