[solved!] Re: [lattice] format and rotation of strip text

https://stat.ethz.ch/pipermail/r-help/2012-November/329509.html

-  without the line above commented out, strip values are (correctly)

                               typo, should be "incorrectly" ^^^^^^^^^

  all 1.123

+  with the line above commented out, strip values are (correctly)
  1.123 .. 5.123

how to round() or signif() the values obtained from array.3d.df$lev
and displayed in the strips?

https://stat.ethz.ch/pipermail/r-help/2012-November/329512.html

[omitted] seems to be a better result:

Indeed! The complete sequence that Worked For Me is

# start example
library(reshape2)
library(lattice)

lon=11
lat=7
lev=5
len=lon*lat*lev
array.3d <- array(data=c(1:len), dim=c(lat, lon, lev))

# Rewrite the array values "more spatially," i.e., row-wise from
# bottom left. If there's a more-R-ish way to fill this array as
# desired, please let me know: I know 'for' loops are deprecated
# in R.

i=1
for (z in 1:lev) {
 for (x in lat:1) {
   for (y in 1:lon) {
     array.3d[x,y,z]=i ; i=i+1
   }
 }
}

# produces (with rows=latitudes and cols=longitudes)
array.3d[,,1]
array.3d[,,lev]

# convert data=array.3d to dataframe with reshape2::melt
array.3d.df <- melt(array.3d, varnames=c("lat","lon","lev"), value.name="conc")
head(array.3d.df)
tail(array.3d.df)

# make level values {longer, "more realistic"}

array.3d.df$lev <- array.3d.df$lev + 0.12345 # truncated below, and ...
# ... below note output from these
head(array.3d.df)
tail(array.3d.df)

# plot "appropriately" for atmospheric data where lev=pressure: use
# * lattice::levelplot
# * one column, since atmospheric levels stack vertically
# * rev(lev), since layers closer to ground level have higher pressure

levelplot(
 conc ~ lon * lat | rev(lev), data=array.3d.df, layout=c(1,lev),
 levs=as.character(round(array.3d.df[['lev']], 1)),
 strip=FALSE,
 strip.left=strip.custom(
   factor.levels=as.character(signif(unique(array.3d.df[['lev']]), 3)),
   strip.levels=TRUE,
   horizontal=TRUE,
   strip.names=FALSE,
   # gotta shrink strip text size to fit strip width:
   # more on that separately
   par.strip.text=list(cex=0.5)
 )
)
# end example