I do agree with Dr Berry that your question failed on several grounds
in adherence to the Posting Guide, so this is off list.
Maybe this will give you guidance that you can apply to your next
question to the list:
> alist <- list("a","b","c")
> blist <- list("ab","ac","ad")
> expand.grid(alist, blist)
Var1 Var2
1 a ab
2 b ab
3 c ab
4 a ac
5 b ac
6 c ac
7 a ad
8 b ad
9 c ad
> apply( expand.grid(alist, blist), 1, function(x) paste(x[1], x[2],
sep=""))
[1] "aab" "bab" "cab" "aac" "bac" "cac" "aad" "bad" "cad"
> clist <- list("AA","BB")
> apply(expand.grid(alist, blist, clist),1,function(x) paste(x[1],
x[2], x[3], sep=""))
[1] "aabAA" "babAA" "cabAA" "aacAA" "bacAA" "cacAA" "aadAA" "badAA"
"cadAA" "aabBB"
[11] "babBB" "cabBB" "aacBB" "bacBB" "cacBB" "aadBB" "badBB" "cadBB"
> dlist <- list(TRUE,FALSE)
> apply(expand.grid(alist, blist, clist, dlist),1,function(x)
paste(x[1], x[2], x[3], (x[4]), sep=""))[8:12]
[1] "badAATRUE" "cadAATRUE" "aabBBTRUE" "babBBTRUE" "cabBBTRUE"
This could get unwieldily if the length of the lists are appreciable,
since the number of rows will be the product of all the lengths. On
the other hand you could create a dataframe indexed by the variables
in expand.grid's output:
> master.df <- data.frame( expand.grid(alist, blist, clist, dlist),
results = apply(expand.grid(alist, blist,
clist,dlist),1,
function(x) paste(x[1], x[2],
x[3], (x[4]), sep="")))
--
David Winsemius
On Dec 22, 2008, at 3:33 PM, Charles C. Berry wrote:
On Mon, 22 Dec 2008, Brigid Mooney wrote:
Hi All,
I'm still pretty new to using R - and I was hoping I might be able
to get
some advice as to how to use 'apply' or a similar function instead
of using
nested for loops.
Unfortunately, you have given nothing that is reproducible.
The details of MyFunction and the exact structure of the list
objects are crucial.
Check out the _Posting Guide_ for hints on how to formulate a
question that will elecit an answer that helps you.
HTH,
Chuck
Right now I have a script which uses nested for loops similar to
this:
i <- 1
for(a in Alpha) { for (b in Beta) { for (c in Gamma) { for (d in
Delta) {
for (e in Epsilon)
{
Output[i] <- MyFunction(X, Y, a, b, c, d, e)
i <- i+1
}}}}}
Where Output[i] is a data frame, X and Y are data frames, and
Alpha, Beta,
Gamma, Delta, and Epsilon are all lists, some of which are numeric,
some
logical (TRUE/FALSE).
Any advice on how to implement some sort of solution that might be
quicker
than these nested 'for' loops would be greatly appreciated.
Thanks!
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Charles C. Berry (858) 534-2098
Dept of Family/Preventive
Medicine
E mailto:cbe...@tajo.ucsd.edu UC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/ La Jolla, San Diego
92093-0901
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
