Paste in a FOR loop

?eval

Carlos J. Gil Bellosta
http://www.datanalytics.com

Michael Pearmain <mpearmain <at> google.com> writes:

Hi All,
I've been having a little trouble using R2HTML and a loop, but can't figure
out where the problem lies, any hints gratefully received.

..

library(R2HTML)
HTMLStart(outdir =
file.path("C://Example_work","R_projects","Dynamic_creative"),filename =
"RMDC_mockup",Title="Mock up for RMDC")

for(group in 1:3){
paste("summary(z.out.", group, sep = "")
paste("summary(s.out.", group, sep = "")
paste("s.out.",group,"$qi$ev", sep = "")
HTMLplot()
}
HTMLStop()

Check documentation on HTMLInsertGraph, and don't forget to change the filename
in the loop, otherwise you always see the last file.

Dieter

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summary(z.out.1)
summary(s.out.1)
hist(s.out.1$qi$ev)...
This seemed a rather long winded way of doing things to me and a simple for
loop should handle this, as later i want it to be dynamic for a number of
groups so my new code is(not working):

...

for(group in 1:3){
paste("summary(z.out.", group, sep = "")
paste("summary(s.out.", group, sep = "")
paste("s.out.",group,"$qi$ev", sep = "")

This just constructs strings.  You actually want to call "summary" on
the value of the variable z.out.1 etc., so constructing the string
"z.out.1" or "summary(z.out.1" [sic] doesn't help.  To call summary on
the value of the variables, you can use:

     summary( get(paste("z.out",group,sep="")) ) ...

But in general, if you're not doing real meta-programming, the
presence of a "get" or even worse an "eval" in your code generally
indicates that you're not organizing your data appropriately.  Why not
have z.out be a *list* of values, so you can just write

    for (group in 1:3) { summary(z.out[[group]]); ...}

Hope this helps,

          -s