Sorry for posting this twice, but I still have not solved this problem
and am hoping for some assistance.
I am attempting to write a function that is flexible enough to respond
to the user providing a formula (with a data= argument) or not (similar
to plot(x,y) versus plot(y~x,data=data)). I have found a method to work
with this in a simple case but am having trouble determining how to
"find" a variable from within the data= argument that is not part of
the
formula. The following code illustrates (I know that
plotrix::thigmophobe.labels() does what this function does) my problem
...
myplot <- function(x,y=NULL,data=NULL,label=NULL) {
if (class(x)=="formula") {
mf <- model.frame(x,data=data)
x <- mf[,2]
y <- mf[,1]
}
if (is.null(y)) stop("Y-axis variable is missing")
plot(x,y)
if (!is.null(label)) text(x,y,label)
}
# dummy data
df <-
data.frame(x=runif(10),y=runif(10),grp=factor(rep(c("Yes","No"),each=5))
)
# both calls work as expected
with(df,myplot(x,y))
myplot(y~x,data=df)
# only first works as I would hope
with(df,myplot(x,y,label=grp))
myplot(y~x,data=df,label=grp)
# this works but is clumsy
myplot(y~x,data=df,label=df$grp)
Any help with how to make this function recognize the "grp" variable
in
"df" when using the formula without having to type "df$grp"
when
supplying it to the "label=" argument would be greatly appreciated.
Thank you in advance.
[[alternative HTML version deleted]]
Hi, It seems to me that you could write a generic function myplot() and have different methods for each class of object (like plot does). Either S3 or S4 classes would do I think. Then it is only a matter of making each method work separately. In particular, the method for a formula could contain the with(data, ) construct to make all the variables accessible to the text() function. HTH, baptiste On 4 Apr 2009, at 23:27, Derek Ogle wrote:> Sorry for posting this twice, but I still have not solved this problem > and am hoping for some assistance. > > > > I am attempting to write a function that is flexible enough to respond > to the user providing a formula (with a data= argument) or not > (similar > to plot(x,y) versus plot(y~x,data=data)). I have found a method to > work > with this in a simple case but am having trouble determining how to > "find" a variable from within the data= argument that is not part of > the > formula. The following code illustrates (I know that > plotrix::thigmophobe.labels() does what this function does) my problem > ... > > > > > > myplot <- function(x,y=NULL,data=NULL,label=NULL) { > > if (class(x)=="formula") { > > mf <- model.frame(x,data=data) > > x <- mf[,2] > > y <- mf[,1] > > } > > if (is.null(y)) stop("Y-axis variable is missing") > > plot(x,y) > > if (!is.null(label)) text(x,y,label) > > } > > > > # dummy data > > df <- > data > .frame(x=runif(10),y=runif(10),grp=factor(rep(c("Yes","No"),each=5)) > ) > > > > # both calls work as expected > > with(df,myplot(x,y)) > > myplot(y~x,data=df) > > > > # only first works as I would hope > > with(df,myplot(x,y,label=grp)) > > myplot(y~x,data=df,label=grp) > > > > # this works but is clumsy > > myplot(y~x,data=df,label=df$grp) > > > > > > Any help with how to make this function recognize the "grp" variable > in > "df" when using the formula without having to type "df$grp" when > supplying it to the "label=" argument would be greatly appreciated. > Thank you in advance. > > > > > > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at 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._____________________________ Baptiste Augui? School of Physics University of Exeter Stocker Road, Exeter, Devon, EX4 4QL, UK Phone: +44 1392 264187 http://newton.ex.ac.uk/research/emag
Try adding this line: label <- eval(substitute(label), df, environment(formula)) On Sat, Apr 4, 2009 at 6:27 PM, Derek Ogle <DOgle at northland.edu> wrote:> Sorry for posting this twice, but I still have not solved this problem > and am hoping for some assistance. > > > > I am attempting to write a function that is flexible enough to respond > to the user providing a formula (with a data= argument) or not (similar > to plot(x,y) versus plot(y~x,data=data)). ?I have found a method to work > with this in a simple case but am having trouble determining how to > "find" a variable from within the data= argument that is not part of the > formula. ?The following code illustrates (I know that > plotrix::thigmophobe.labels() does what this function does) my problem > ... > > > > > > myplot <- function(x,y=NULL,data=NULL,label=NULL) { > > ?if (class(x)=="formula") { > > ? ?mf <- model.frame(x,data=data) > > ? ?x <- mf[,2] > > ? ?y <- mf[,1] > > ?} > > ?if (is.null(y)) stop("Y-axis variable is missing") > > ?plot(x,y) > > ?if (!is.null(label)) text(x,y,label) > > } > > > > # dummy data > > df <- > data.frame(x=runif(10),y=runif(10),grp=factor(rep(c("Yes","No"),each=5)) > ) > > > > # both calls work as expected > > with(df,myplot(x,y)) > > myplot(y~x,data=df) > > > > # only first works as I would hope > > with(df,myplot(x,y,label=grp)) > > myplot(y~x,data=df,label=grp) > > > > # this works but is clumsy > > myplot(y~x,data=df,label=df$grp) > > > > > > Any help with how to make this function recognize the "grp" variable in > "df" when using the formula without having to type "df$grp" when > supplying it to the "label=" argument would be greatly appreciated. > Thank you in advance. > > > > > > > ? ? ? ?[[alternative HTML version deleted]] > > ______________________________________________ > R-help at 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. >