Thanks Peter. Sorry for this question... I really need holidays.
Cheers.
On 27/07/2012 13:30, peter dalgaard wrote:
On Jul 27, 2012, at 11:23 , Stéphane Dray wrote:
Dear list,
I try to use the eval function and to understand its functionning. I tried:
xy <- "global"
f1 <- function(){
xy <- "f1"
a1 <- eval.parent(xy)
b1 <- eval(xy, sys.frame(0))
print(paste("a1 =",a1))
print(paste("b2 =",b1))
f3 <- function(){
print("----F3----")
a3 <- eval.parent(xy)
b3 <- eval(xy, sys.frame(0))
print(paste("a3 =",a3))
print(paste("b3 =",b3))
}
f2()
f3()
}
f2 <- function(){
print("----F2----")
a2 <- eval.parent(xy)
b2 <- eval(xy, sys.frame(0))
print(paste("a2 =",a2))
print(paste("b2 =",b2))
}
f1()
f2()
I obtain the following results (and add as comments what I would expect after
reading the doc). I really do not understand why the evaluation in sys.frame(0)
(i.e. global environment) did not work. Moreover, the evaluation through
eval.parent should be linked to the environment of the caller and not the
definition (so I do not understand why f2 and f3 produces different results).
f1()
[1] "a1 = f1" ## global ?
[1] "b2 = f1" ## global
[1] "----F2----"
[1] "a2 = global" ## f1
[1] "b2 = global" ## global
[1] "----F3----"
[1] "a3 = f1" ## f1
[1] "b3 = f1" ## global
f2()
[1] "----F2----"
[1] "a2 = global"
[1] "b2 = global"
Any help would be appreciated, Thanks.
Try quote(xy) in a number of places....
--
Stéphane DRAY (stephane.d...@univ-lyon1.fr)
Laboratoire BBE-CNRS-UMR-5558, Univ. C. Bernard - Lyon I
43, Bd du 11 Novembre 1918, 69622 Villeurbanne Cedex, France
Tel: 33 4 72 43 27 57 Fax: 33 4 72 43 13 88
http://pbil.univ-lyon1.fr/members/dray/
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