My intention is to include certain columns if they meet certain criteria.
For example, if "b" is one of the columns of a1, then keep otherwise don't.
HTH..
santosh
On Fri, Jan 10, 2014 at 1:01 PM, MacQueen, Don <macque...@llnl.gov> wrote:
> Apologies, but all that ifelse() stuff is too hard to follow.
>
> What I would do is compute a character vector of column names to keep,
> then do
>
> a1[ , names.to.keep]
>
> -Don
>
> --
> Don MacQueen
>
> Lawrence Livermore National Laboratory
> 7000 East Ave., L-627
> Livermore, CA 94550
> 925-423-1062
>
>
>
>
>
> On 1/10/14 12:53 PM, "Santosh" <santosh2...@gmail.com> wrote:
>
> >Dear Rxperts...
> >
> >I would like to conditionally include an element (as a column) in a
> >dataframe. Please see the sample code below:
> >
> >There is a correction to the earlier post.. my apologies...
> >a1 <- data.frame(P=rep(1,10),Qr=LETTERS[1:10],b=letters[1:10],
> >R=rep(c("A","B"),each=5))
> >
> > lc1 <- list(C1 = "P",C2 =
> >ifelse(is.element("Q",names(a1)),"Q",ifelse(is.element("b",names(a1)),"b",
> >NULL)),C3="R")
> > lc2 <- list(C1 = "P",C2 =
> >ifelse(is.element("Q",names(a1)),"Q",ifelse(is.element("b",names(a1)),"b",
> >NULL)),
> >C3=ifelse(is.element("Ra",names(a1)),"Ra",NULL))
> >*The error for the above:*
> >Error in ifelse(is.element("Ra", names(a1)), "Ra", NULL) :
> > replacement has length zero
> >In addition: Warning message:
> >In rep(no, length.out = length(ans)) :
> > 'x' is NULL so the result will be NULL
> >
> >a2 <- subset(a1, sel=unlist(lc1)) # this works
> >a3 <- subset(a1, sel=unlist(lc2)) # this doesn't work
> >
> >Is there a way to dynamically include columns in a dataframe?
> >
> >Regards,
> >santosh
> >
> >
> >On Fri, Jan 10, 2014 at 12:45 PM, Santosh <santosh2...@gmail.com> wrote:
> >
> >> Dear Rxperts...
> >>
> >> I would like to conditionally include an element (as a column) in a
> >> dataframe. Please see the sample code below:
> >>
> >> a1 <-
> >>
> >>data.frame(P=rep(1,10),Qr=LETTERS[1:10],b=letters[1:10],R=rep(c("A","B"),
> >>each=5))
> >>
> >> lc1 <- list(C1 = "P",C2 =
> >>
> >>ifelse(is.element("Q",names(a1)),"Q",ifelse(is.element("b",names(a1)),"b"
> >>,NULL)),C3="R")
> >> lc2 <- list(C1 = "P",C2 =
> >>
> >>ifelse(is.element("Q",names(a1)),"Q",ifelse(is.element("b",names(a1)),"b"
> >>,NULL)),C3="Ra")
> >>
> >> a2 <- subset(a1, sel=unlist(lc1)) # this works
> >> a3 <- subset(a1, sel=unlist(lc2)) # this doesn't
> >>
> >> Is there a way to dynamically include columns in a dataframe?
> >>
> >> Regards,
> >> santosh
> >>
> >
> > [[alternative HTML version deleted]]
> >
> >______________________________________________
> >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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