[R] Iterations

[rkevinburton at charter.net]

Thank you.

?for just gives me a + rompt indicating that I need to supply more input. The same with ?while and ?repeat. Help(for) yelds:

 > help(for)
Error: unexpected ')' in "help(for)"

But thanks for the tip.

Keivn

---- Erik Iverson <iverson at biostat.wisc.edu> wrote: 
> If you read the help page, ?for, you might have seen under "Value", that
> 
>       'for', 'while' and 'repeat' return the value of the last
>       expression evaluated (or 'NULL' if none was), invisibly.
> 
> So if you want to see the values, print() them.
> 
> In general, from the first part of your message, it looks like you're 
> trying to run some analysis on different subgroups of your data.
> 
> You may want to try the functions tapply, by, aggregate, ave, etc., for 
> this purpose rather than using 'for' loops.
> 
> Best,
> Erik Iverson
> 
> 
> rkevinburton at charter.net wrote:
> > I have a command that reads in some data:
> > 
> > x <- read.csv("Sales2007.dat", header=TRUE)
> > 
> > Then I try to organize the data:
> > 
> > sc <- split(x, list(x$Category, x$SubCategory), drop=TRUE)
> > 
> > Then I want to iterate through the data. I was able to get the following to run on the R console:
> > 
> > for(i in 1:length(sc))
> > {
> >     sum(sc[[i]]$Quantity)
> > }
> > 
> > But notiing is primted on the console. I find that:
> > 
> > for(i in 1:100)
> > {
> >     i
> > }
> > 
> > Also does't output anything? I am probably making a wrong assumption here. Why desn't the loop seem to output anyything?
> > 
> > Thank you.
> > 
> > Kevin
> > 
> > ______________________________________________
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