Re: [R] attributing values to dataframe positions following eval

From: John Kane <jrkrideau_at_yahoo.ca>
Date: Tue, 08 Jul 2008 07:12:17 -0700 (PDT)


Does not just
polyList[[1]])[1, 1] <- 5

work?

> From: Stephane Bourgeois <sb20_at_sanger.ac.uk>
> Subject: [R] attributing values to dataframe positions following eval
> To: r-help@r-project.org
> Received: Tuesday, July 8, 2008, 5:40 AM
> Hi everybody,
>
>
>
> I've been looking around, but can't seem to find
> the answer.
>
>
>
> I get a list of names (which vary, so I never know them in
> advance), and
> transform them into variables, each of which is a
> dataframe, using
> assign:
>
>
>
> polyList <- c("rs123", "rs124",
> "rs555", "rs000")
>
> numPoly <- length(polyList)
>
>
>
> for (k in 1:numPoly) {
>
> assign(polyList[k], data.frame(matrix(NA, ncol=3,
> nrow=3)))
>
> }
>
>
>
> polyList <- lapply(polyList, as.name)
>
>
>
> I can see the resulting dataframe associated to rs123 (for
> example)
> using:
>
>
>
> > eval(polyList[[1]])
>
> X1 X2 X3
>
> 1 NA NA NA
>
> 2 NA NA NA
>
> 3 NA NA NA
>
>
>
> And see the value in row 1, column 1 with:
>
>
>
> > eval(polyList[[1]])[1,1]
>
> [1] NA
>
>
>
> Now, I want to change the values in the dataframe...
> that's what I can't
> manage to do:
>
>
>
> > eval(polyList[[1]])[1,1] <- 5
>
> Error in eval(polyList[[1]])[1, 1] <- 5 :
>
> could not find function "eval<-"
>
>
>
> Anybody has an idea on how to do that?
>
>
>
> Thank you,
>
>
>
> Stephane
>
>
>
> PS: yes, I'm aware that using arrays and dataframes
> instead of going
> through the creation of variables may be more practical,
> but the context
> is much more complex than the presented example (and in
> that specific
> case, having these variables is a requirement)
>
>
>
>
>
>
> --
> The Wellcome Trust Sanger Institute is operated by Genome
> Research
>
> Limited, a charity registered in England with number
> 1021457 and a
> compa
> ny registered in England with number 2742969, whose
> registered
> office is 2
> 15 Euston Road, London, NW1 2BE.
>
>
>
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>
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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. Received on Tue 08 Jul 2008 - 14:15:57 GMT

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