On Jun 18, 2012, at 5:25 PM, elmo wrote:
Hi all,
I'm new to R, have been reading books and trying to get started
coding too.
The first thing of substance I've been trying to do is to create a
function
to return a list of all binary trees of a list of ordinals. So, for
example, an input of list(3,1,2,4) would return:
Please do not cross-post (but DO read the Posting Guide where this was
is requested). You have already gotten an answer on StackOverflow.
--
David.
list(list(1, list(2, list(3, 4))),
list(1, list(list(2, 3), 4)),
list(list(1, 2), list(3, 4)),
list(list(1, list(2, 3)), 4),
list(list(list(1, 2), 3), 4))
I've been trying recursions but nothing I've written has been both
complete
and correct in the final formatting, and I'm sort of clueless when
it comes
to recursive wrappers. For example, one function I wrote,
g=function(x) {
len.x = length(x);
if (len.x > 2)
{
y=list()
for (i in 1:(len.x-1))
y[[i]] = list(g(x[1:i]),g(x[-i:-1]))
return(y)
}
else return(x)
}
trim = function(x) {
for (i in 1:length(x)) {
if ((length(x[[i]]) == 1) && is.list(x[[i]]))
x[[i]] = x[[i]][[1]]
}
return(x)
}
findBinTreesOrd=function(x) {
x.lst = sort(unlist(x))
all.bin.trees = g(x.lst)
trim(all.bin.trees)
}
returns the trees in a compact, recursively nested form that I
haven't found
a way to expand to the format that I desire. Any help in either
writing a
wrapper for that or a different approach to achieve what I'm trying
to get
would be greatly appreciated--again, I'm quite new to R and am still
shaky
with the powers and constraints that come with it.
LM
--
View this message in context:
http://r.789695.n4.nabble.com/Listing-all-binary-trees-of-an-ordinal-set-tp4633753.html
Sent from the R help mailing list archive at Nabble.com.
______________________________________________
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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.
David Winsemius, MD
West Hartford, CT
______________________________________________
R-help@r-project.org mailing list
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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.
