lattice default aspect fails for some data sets (PR#1744)

Full_Name: Dieter Menne
Version: 1.5.1
OS: Win2000
Submission from: (NULL) (212.185.252.129)


Lattice Version: 0.5-3

There is a problem in print.trellis that can lead to an
error reported as follows:

Error in rep(x$x.between, length = cols.per.page - 1) : 
        invalid number of copies in "rep"
In addition: Warning messages: 
1: argument lengths differ in: split(x, f) 
2: NAs introduced by coercion 

The error only turns up with certain data sets and 
device/aspect ratios and can be tracked down to the following:

    if(x$layout[1]==0) { # using device dimensions to
        ddim <- par("din") # calculate default layout
        device.aspect <- ddim[2]/ddim[1]
        panel.aspect <- if(layout.respect) panel.height else 1

        plots.per.page <- x$layout[2]
##### m can be zero, depending on data
        m <- round(sqrt(x$layout[2] * device.aspect/panel.aspect))
        n <- ceiling(x$layout[2]/m)
        x$layout[1] <- n


Quick Fix (works for me, but not tested with different data sets):

replace "round" by "ceiling"

Workaround (always works): Use explicit "aspect".