Dear all
I am trying to find the best way to handle large fields in reference
classes.
As the code below shows assignment via <<- causes many copies to be made if
the subsetting is extensive (in modb1). This can cause R to run out of
memory. Creating a local copy and using the optimisation in <- is the best
solution I have found so far (in modb2) - but it is not really much better
than ordinary functions using call by value and then reassigning.
Is there a reason why optimisation does not occur for <<- ? Or is their a
better solution for reference classes?
Regards
Giles
A <- setRefClass("A", fields=list(b="vector"))
A$methods(
initialize=function() {
b <<- 1:10000
},
modb1=function() {
# simple subsetting for illustration
for(i in 2:length(b)) b[i] <<- b[i-1] + 1
},
modb2=function() {
bb <- b
for(i in 2:length(b)) bb[i] <- bb[i-1] + 1
b <<- bb
}
)
a <- new("A")
tracemem(a$b)
a$modb1()
a$modb2()
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