[R] slide show with R

Berton Gunter gunter.berton at gene.com
Tue Mar 29 23:18:29 CEST 2005


One possible strategy:

see ?readLines

Write a text file with your R commands. Then
write a little function that opens a connection to the file and runs a loop
to:

1)read a line from your file via readLines
2) cat() the line on your terminal
3) prompt via readline to execute it.

You'll have to get a little fancy to check for expressions that span several
lines and check for the end of file, but this should work, I think.

Cheers,

-- Bert Gunter
Genentech Non-Clinical Statistics
South San Francisco, CA
 
"The business of the statistician is to catalyze the scientific learning
process."  - George E. P. Box
 
 

> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of 
> George_Heine at blm.gov
> Sent: Tuesday, March 29, 2005 12:54 PM
> To: R-Help
> Subject: [R] slide show with R
> 
> 
> 
> 
> 
> Trying to use R to build an interactive "slide show", to be 
> displayed on a
> projector.  The purpose of the presentation is to show how one could
> construct a simple graph using R.  It is meant as a general 
> overview rather
> than as detailed instruction.
> 
> For example, something like the following sequence of commands.    At
> lecture time, I want the interpreter to read these commands 
> one at a time
> from a file, display and execute the command, (or two or 
> three commands)
> and then wait for another prompt.
> 
> pale.yellow="#ffff99"
> par(bg=pale.yellow)
> plot(c(0,2*pi),c(-1,1),type="n",ylab="",yaxt="n")
> mirror<-function(t) { c(t,rev(2*max(t)-t)) }
> z<-log(1:1000)/log(1000)
> zz<-z*pi/2
> zzz<-mirror(mirror(zz))
> polygon(zzz,sin(25*zzz)*sin(zzz),border="blue")
> polygon(zzz,sin(5*zzz)*sin(zzz),border="green")
> polygon(zzz,sin(zzz),lwd=2)
> points(zzz,rep(0,length(zzz)),col="red",pch="|")
> 
> 
> Wrapping the following around each command works, sort of :
> 
> a<-expression(<command>)
> x<-readline(a)
> eval(a)
> 
> However, this doesn't work properly for the function 
> definition, and it
> gets very clumsy to display two or three lines as a block and then
> evaluate.
> 
> Any help would be much appreciated.
> 
> 
> <>=<>=<>=<>=<>=<>=<>=<>=<>=<>=<>
> George Heine, PhD
> Mathematical Analyst
> National IRM Center
> U.S. Bureau of Land Management
> voice   (303) 236-0099
> fax       (303) 236-1974
> cell      (303) 905-5382
> pager   gheine at my2way.com
> <>=<>=<>=<>=<>=<>=<>=<>=<>=<>=<>
> 
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