[R] slide show with R

[Greg Snow]

Another approach is to put your commands below into a text file.

Add a line like:

tmp <- readline('Press Enter to Continue:')

everywhere you want to pause.

Then do:

source('path/to/text/file', echo=T)

it will print out the commands and execute them, but everytime it gets
to the tmp <- ... line it will pause and wait for you to press enter
before continuing on.  you can discuss the lines that have just been
executed and the current plot, then press enter for the next chunk.

hope this helps,




Greg Snow, Ph.D.
Statistical Data Center
greg.snow at ihc.com
(801) 408-8111

>>> <George_Heine at blm.gov> 03/29/05 01:54PM >>>

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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