[Rd] problem with cut.Date/date plotting in ggplot2

[Ben Bolker]

   I've hit a problem in ggplot2 which I can trace back to cut.Date ,
which is either a bug or (??) ggplot2 trying to do something it
shouldn't with cut.Date (although its use of cut.Date seems OK).

  Apparently any (?) call of the form

cut(as.Date("2008-07-07"),"weeks")

where the date *begins the week*, gives the error

Error in 1:(1 + max(which(breaks < maxx))) :
  result would be too long a vector
In addition: Warning message:
In max(which(breaks < maxx)) :
  no non-missing arguments to max; returning -Inf

  In particular, try:

d <- seq.Date(as.Date("2008-07-05"),as.Date("2008-07-08"),by="days")
weekdays(d)

cut(d[1],"weeks") ## OK
cut(d[2],"weeks") ## OK
cut(d[3],"weeks") ## Monday -- breaks
cut(d[4],"weeks") ## OK

cut(d[1],"weeks",start.on.monday=FALSE) ## OK
cut(d[2],"weeks",start.on.monday=FALSE) ## Sunday -- breaks
cut(d[3],"weeks",start.on.monday=FALSE) ## OK
cut(d[4],"weeks",start.on.monday=FALSE) ## OK

  The particular line that fails within cut.Date is

breaks <- breaks[1:(1 + max(which(breaks < maxx)))]

  but I haven't figured out enough about what's going on
to be able to suggest a fix ...

  cheers
    Ben Bolker

session info:

> sessionInfo()
R version 2.7.2 (2008-08-25)
i486-pc-linux-gnu

locale:
LC_CTYPE=en_US.UTF-8;LC_NUMERIC=C;LC_TIME=en_US.UTF-8;LC_COLLATE=en_US.UTF-8;LC_MONETARY=C;LC_MESSAGES=en_US.UTF-8;LC_PAPER=en_US.UTF-8;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC_MEASUREMENT=en_US.UTF-8;LC_IDENTIFICATION=C

attached base packages:
[1] splines   grid      stats     graphics  grDevices utils     datasets
[8] methods   base

other attached packages:
[1] ggplot2_0.7        MASS_7.2-44        RColorBrewer_1.0-2 proto_0.3-8

[5] reshape_0.8.1      plyr_0.1


 Here's the context in which I encountered the problem:

library(ggplot2)
tdat <- data.frame(date=seq.Date(as.Date("2008-07-07"),
                     as.Date("2008-10-10"),by="day"),
                   x=1:96)
q2 = qplot(date,x,data=tdat,geom="smooth")
print(q2+geom_point())

  I can track the problem down to a call like

floor_date(as.Date("2008-07-07"),"weeks")

and digging further in, I can narrow it down to
the issue above.