S3 method conflict with zoo

[joshuaulrich]

Kurt Hornik noticed, and Achim Zeileis reported that zoo's method for as.zoo.xts is overwritten by xts. So zoo's S3 registry entries are overwritten when xts is loaded.

It looks like the xts method only exists because it didn't exist in zoo at the time. I think the package that owns the class should define the conversion
method, so the as.zoo* methods should be in zoo.

Achim noted the difference in as.zoo.xts() between zoo and xts is small (with xts being better). He thinks we should just move xts' version into zoo, and I agree.

[joshuaulrich]

I tried to address this and got a couple test failures when I removed xts' method without updating zoo's. The code below illustrates the difference:

R> x <- xts::.xts(, 1)
R> xts:::as.zoo.xts(x)
Data:
numeric(0)

Index:
[1] "1969-12-31 18:00:01 CST"
R> zoo:::as.zoo.xts(x)
1969-12-31 18:00:01
                 NA

So it seems like we would need a zoo release prior to removing it from xts and updating the zoo dependency version. Or maybe there's a way to only register it in xts if zoo is less than a specific version.

Achim suggested try using an .onLoad() hook similar to that in zoo/R/zzz.R which conditionally registers ggplot2 methods.

[linusjf]

So has this been fixed? I'm getting the same message on R for Termux, version 3.6.2.

[joshuaulrich]

Yes, this is fixed. I'm working with CRAN to get the patched version released.

[linusjf]

Ok, thanks. I've suppressed the messages using suppressMessages.