I wrote a dirty hack last time I faced this problem, I'll be curious
to see what is the proper way of dealing with the scoping and
evaluation rules.
library(datasets)
myfunction<-function(table, extraction) {
table2<-subset(table,extraction)
return(table2)
}
condition1 <- quote(iris$Species=="setosa") # I'm not sure how to
evaluate within the environment, perhaps you could use with(table,
subset(table, extraction) ) in your function
condition2 <- bquote(.(condition1) & iris$Sepal.Width < 3.5) # say,
if you want to concatenate several conditions together
myfunction(iris, extraction= eval(condition1))
myfunction(iris, extraction= eval(condition2))
Best wishes,
baptiste
On 17 Dec 2008, at 19:07, GOUACHE David wrote:
Hello R-helpers,
I'm writing a long function in which I manipulate a certain number
of datasets. I want the arguments of said function to allow me to
adapt the way I do this. Among other things, I want my function to
have an argument which I will pass on to subset() somewhere inside
my function. Here is a quick and simplified example with the iris
dataset.
myfunction<-function(table, extraction) {
table2<-subset(table, extraction)
return(table2) }
myfunction(iris, extraction= Species=="setosa")
############## end
What I would like is for this function to return exactly the same
thing as :
subset(iris, Species=="setosa")
Thanks for your help.
Regards,
David Gouache
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_____________________________
Baptiste Auguié
School of Physics
University of Exeter
Stocker Road,
Exeter, Devon,
EX4 4QL, UK
Phone: +44 1392 264187
http://newton.ex.ac.uk/research/emag
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
