These are all great resposes but I think I should have given a
slightly more complete description of the problem.
I am using the quantmod package and I have called getSymbols with a
character vector that has a list of stock symbols. For example:
library("quantmod")
list=c("MSFT","AAPL","ORCL")
getSymbols(list)
this returns 3 objects (MSFT,AAPL, ORCL)
now imagine that I want to use the Delt function (also in quantmod) to
calculate the percent difference for each of these stocks using their
closing price.
each closing price is SYMBOL$SYMBOL.Close (can also be retrieved with
Cl(SYMBOL)
I want to construct the call to Delt with the symbols in list appended
with $SYMBOL.Adjusted
in other words I want a way to create
Delt(MSFT$MSFT.Close) merged with Delt(AAPL$AAPL.Close) and so on
(one object having the result of the Delt function for each stock).
I am sure that there are many ways to solve this particular problem.
Perhaps what I need to understand is how to take the characters in the
list and construct an expression and then evaluate the expression.
On Feb 5, 2009, at 5:50 PM, <markle...@verizon.net> wrote:
> Hi: there's mget but I couldn't figure out how to use it. if you
> figure
> it out, let me know.
> I'm sure one of the guRus will reply with something that uses mget.
> List
> is slow now
> because Europe is sleeping. Good luck.
>
>
>
>
> On Thu, Feb 5, 2009 at 5:42 PM, Ira Fuchs wrote:
>
> > Thanks, that is better but doesn't actually solve my problem which
> is
> > that n is an arbitrary length vector and I'd like to find a way that
> > avoids having to enumerate the elements of the character vector.
> > Thanks,
> > Ira
> > ----- Original Message -----
> > From: markle...@verizon.net <markle...@verizon.net>
> > To: Fuchs Ira <irafu...@gmail.com>
> > Sent: Thu Feb 05 17:25:39 2009
> > Subject: RE: [R] eval and as.name
> >
> >
> > Hi: below works but it's not much shorter than yours. there must
> be a
> > better way so I'm sending off line in order to encourage better
> > replies.
> >
> > sum(get(n[1]),get(n[2]))
> >
> >
> >
> >
> > On Thu, Feb 5, 2009 at 5:10 PM, Fuchs Ira wrote:
> >
> >> I'm sure there is a more general way to ask this question but how
> do
> >> you use the elements of a character vector as names of objects in
> an
> >> expression?
> >> For example, say you have:
> >>
> >> a = c(1,3,5,7)
> >> b = c(2,4,6,8)
> >>
> >> n=c("a","b")
> >>
> >> and you want to use the names a and b in a function (e.g. sum)
> >>
> >> sum(eval(as.name(n[1])),eval(as.name(n[2])))
> >>
> >> works but
> >>
> >> what is a simpler way to effect this level of indirection?
> >>
> >> ______________________________________________
> >> 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.
>
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