Arne Henningsen wrote:
Hi!
I noticed that there is a (minor) bug either the command all.equal()
or in the "plm" package. I demonstrate this using an example taken
from the documentation of plm():
I'm not sure this is a bug, but I'd call it at least a design flaw. The
problem is that the length.Formula method in the Formula package (which
plm depends on) returns a vector of length 2. Now there's nothing in R
that requires length() to return a scalar, but all.equal assumes it
does, and I'd guess there are lots of other places this assumption is made.
Duncan Murdoch
======================================
R> data("Produc", package="plm")
R> zz <- plm(log(gsp)~log(pcap)+log(pc)+log(emp)+unemp,
+ data=Produc, index=c("state","year"))
R> all.equal(zz,zz)
[1] TRUE
Warning message:
In if (length(target) != length(current)) return(paste("target,
current differ in having response: ", :
the condition has length > 1 and only the first element will be used
all.equal(zz$formula,zz$formula)
[1] TRUE
Warning message:
In if (length(target) != length(current)) return(paste("target,
current differ in having response: ", :
the condition has length > 1 and only the first element will be used
class(zz$formula)
[1] "pFormula" "Formula" "formula"
======================================
The last commands show that the warning message comes from comparing
the elements "formula", which are of the class "pFormula" (inheriting
from "Formula" and "formula"). It would be great if this issue could
be fixed in the future.
Thanks a lot,
Arne
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