On Thu, 11 Aug 2005, David L. Van Brunt, Ph.D. wrote:
Ok, here's an english pseudo coded version of what I'd like to do...
10 columns of (somedata)
names(somedata): C1 C2 C3 C4 C5
Loop through each column
FOR ColName = C1 through C5
Compute a new column, named "ColNameA" = some result for each row
Compute another new Column named ColNameB" = some other result for each row
NEXTColName
A direct translation is
for(name in names(somedata)){
somedata[[paste(name,"A",sep="")]]<-some.result(somedata[[name]])
somedata[[paste(name,"B",sep="")]]<-some.other.result(somedata[[name]])
}
Possibly more efficient is
some.more.data <- lapply(somedata, some.result)
names(some.more.data)<-paste(names(somedata),"A",sep="")
yet.more.data <- lapply(somedata, some.other.result)
names(yet.more.data)<-paste(names(somedata),"B",sep="")
somedata<-cbind(somedata, some.more.data, yet.more.data)
-thomas
Desired Result:
Names(somedata): C1 C1A C1B C2 C2A C2B C3 C3A C3B C4 C4A C4B C5 C5A C5B
So, basically, my question is how to both address and assign the names of
the variables rather than the values of the variables while coding my loop.
I hope that's clearer... kind of hard to explain!
On 10 Aug 2005 21:55:01 +0200, Peter Dalgaard <[EMAIL PROTECTED]>
wrote:
"David L. Van Brunt, Ph.D." <[EMAIL PROTECTED]> writes:
Ok, I know R isn't an optimal environment for looping (or so I've heard)
but
I have a need to loop through columns of data and create new columns of
data
based on calculations within rows...
I'm sure there's a help file, but I'm not sure what search terms to use
to
find it! The problem is that these new columns need to have names that I
can
later access... Like NewVar1, NewVar2, etc....
In php I'd call this "indirection" but I'm not sure what to call it in R
so
that I can find instructions on how to create, name, and address the
values
stored this way...
any gentle nudges in the right direction would be greatly appreciated!
A little more information about what you're actually trying to do and
I'm sure someone will give you a nudge with a sledgehammer...
At present, your description is just that little bit too nebulous.
--
O__ ---- Peter Dalgaard ?ster Farimagsgade 5, Entr.B
c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907
--
---------------------------------------
David L. Van Brunt, Ph.D.
mailto:[EMAIL PROTECTED]
[[alternative HTML version deleted]]
Thomas Lumley Assoc. Professor, Biostatistics
[EMAIL PROTECTED] University of Washington, Seattle
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