On 05/04/2019 9:03 a.m., Therneau, Terry M., Ph.D. via R-devel wrote:
This arose in testing [.terms and has me confused.
data(esoph) # use a standard data set
t0x <- terms(model.frame( ~ tobgp, data=esoph))
t1 <- terms(model.frame(ncases ~ agegp + tobgp, data=esoph))
t1x <- (delete.response(t1))[-1]
> all.equal(t0x, t1x)
[1] TRUE
# the above is wrong, because they actually are not the same
> all.equal(attr(t0x, 'dataClasses'), attr(t1x, 'dataClasses'))
[1] "Names: 1 string mismatch"
[2] "Lengths (1, 2) differ (string compare on first 1)"
As documented, all.equal() is generic, with methods for different
classes. The classes of both t0x and t1x are
c("terms","formula")
with no all.equal.terms method, so all.equal.formula is called. That
method isn't specifically documented, but you can see its definition as
function (target, current, ...)
{
if (length(target) != length(current))
return(paste0("target, current differ in having response: ",
length(target) == 3L, ", ", length(current) == 3L))
if (!identical(deparse(target), deparse(current)))
"formulas differ in contents"
else TRUE
}
So the issue is that deparse(t0x) and deparse(t1x) give the same strings
with no attributes shown, even though "showAttributes" is set by
default. I haven't traced through the C code to see where things are
going wrong.
Duncan Murdoch
> sessionInfo()
R Under development (unstable) (2019-04-05 r76323)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 18.04.2 LTS
Matrix products: default
BLAS: /usr/local/src/R-devel/lib/libRblas.so
LAPACK: /usr/local/src/R-devel/lib/libRlapack.so
locale:
[1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C
[3] LC_TIME=en_US.UTF-8 LC_COLLATE=C
[5] LC_MONETARY=en_US.UTF-8 LC_MESSAGES=en_US.UTF-8
[7] LC_PAPER=en_US.UTF-8 LC_NAME=C
[9] LC_ADDRESS=C LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C
attached base packages:
[1] stats graphics grDevices utils datasets methods base
loaded via a namespace (and not attached):
[1] compiler_3.7.0 tools_3.7.0
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