[Rd] as.matrix.data.frame() warning for POSIXt columns

as.matrix.data.frame() issues a spurious warning for POSIXt columns in R-1.9.1:

R> x <- data.frame(date=as.POSIXct("2004-07-20")) R> as.matrix(x)

     date
   1 "2004-07-20"
   Warning message: longer object length is not a multiple of shorter    object length in: cl == c("Date", "POSIXct", "POSIXlt")

This bug also affects write.table(x), which uses as.matrix.data.frame(x). It arises because the function is comparing the column class, which is a vector of length 2, to a vector of possible values of length 3, using == instead of %in%.

It was discussed in R-help on May 24,2004 by Don MacQueen <macq@llnl.gov> and Brian Ripley <ripley@stats.ox.ac.uk>, where Brian Ripley said:   BDR> The Warning is wrong, though, and will be fixed. but it is still there as of R-patched_2004-07-20.

The following patch to R-1.9.1/src/library/base/R/dataframe.R ought to do it: agate> diff dataframe.R dataframe.new.R 1044c1044
< any(cl == c("Date", "POSIXct", "POSIXlt"))))

---


>              any(cl %in% c("Date", "POSIXct", "POSIXlt"))))



-- 
                              -- David Brahm (brahm@alum.mit.edu)

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