Addressing x and y in aes by variable number
I strongly suggest using aes_q
instead of passing vectors to aes
(@Arun's answer). It may look a bit more complicated, but it is more flexible, when e.g. updating the data.
showplot1 <- function(indata, inx, iny){
p <- ggplot(indata,
aes_q(x = as.name(names(indata)[inx]),
y = as.name(names(indata)[iny])))
p + geom_point(size=4, alpha = 0.5)
}
And here's the reason why it is preferable:
# test data (using non-standard names)
testdata<-data.frame(v1=rnorm(100), v2=rnorm(100), v3=rnorm(100), v4=rnorm(100), v5=rnorm(100))
names(testdata) <- c("a-b", "c-d", "e-f", "g-h", "i-j")
testdata2 <- data.frame(v1=rnorm(100), v2=rnorm(100), v3=rnorm(100), v4=rnorm(100), v5=rnorm(100))
names(testdata2) <- c("a-b", "c-d", "e-f", "g-h", "i-j")
# works
showplot1(indata=testdata, inx=2, iny=3)
# this update works in the aes_q version
showplot1(indata=testdata, inx=2, iny=3) %+% testdata2
Note: As of ggplot2 v2.0.0 aes_q()
has been replaced with aes_()
to be consistent with SE versions of NSE functions in other packages.
Your problem is that aes
doesn't know your function's environment and it only looks within global environment
. So, the variable dat
declared within the function is not visible to ggplot2
's aes
function unless you pass it explicitly as:
showplot1<-function(indata, inx, iny) {
dat <- indata
p <- ggplot(dat, aes(x=dat[,inx], y=dat[,iny]), environment = environment())
p <- p + geom_point(size=4, alpha = 0.5)
print(p)
}
Note the argument environment = environment()
inside the ggplot()
command. It should work now.