Edna Bell wrote:
Hi R users!
I was looking at some of the example code for the "environment"
function. Here it is:
e1 <- new.env(parent = baseenv()) # this one has enclosure package:base.
e2 <- new.env(parent = e1)
assign("a", 3, envir=e1)
ls(e1)
ls(e2)
exists("a", envir=e2) # this succeeds by inheritance
exists("a", envir=e2, inherits = FALSE)
exists("+", envir=e2) # this succeeds by inheritance
My question is: how can "a" exist in e2 when the ls(e2) gives
character(0), please?
It actually doesn't. From the code above here's the inheritance tree for
the environments:
baseenv() => e1 => e2
When you call exists() on the e2 environment, it actually fails. However
since the inherits flag is TRUE by default, exists() searches through
the inherited environments and finds "a" in e1. So, exists will tell you
that it found "a", just not where it found "a".
However, if you set inherits=FALSE, then exists() searches only in the
specified environment.
HTH
Jeff
--
http://biostat.mc.vanderbilt.edu/JeffreyHorner
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