[R-sig-Geo] Harmonizing the sizes of side-by-side spplots

[Edzer Pebesma]

With the help of Deepayan Sarkar, lattice_0.20-7 (on r-forge) lets you
control the key widths; the following two examples (different sized key
right, key bottom) come out with identical map extents (cartographic
scales). Thanks Deepayan!

require(gstat)
data(jura)
coordinates(jura.grid) <- ~ Xloc + Yloc
gridded(jura.grid) <- T
fullgrid(jura.grid) <- T
p1 <- spplot(jura.grid, zcol="Landuse", col.regions=terrain.colors(4))
p2 <- spplot(jura.grid, zcol="Rock", col.regions=bpy.colors(5))
require(lattice)
print(p1, split=c(1,1,2,1), more=T)
print(p2, split=c(2,1,2,1), more=F)

oopt <- lattice.options()
lattice.options(layout.widths =
        list(key.right = list(x = 3,
                 units = "cm", data = NULL)))
print(p1, split=c(1,1,2,1), more=T)
print(p2, split=c(2,1,2,1), more=F)
lattice.options(oopt)

loadMeuse()
p3 = spplot(meuse, "zinc", col.regions = bpy.colors())
p4 = spplot(meuse, "zinc", col.regions = bpy.colors(), cuts = 7)

print(p3, split=c(1,1,2,1), more=T)
print(p4, split=c(2,1,2,1), more=F)

oopt <- lattice.options()
lattice.options(layout.heights =
        list(key.bottom = list(x = 4,
                 units = "cm", data = NULL)))
print(p3, split=c(1,1,2,1), more=T)
print(p4, split=c(2,1,2,1), more=F)
lattice.options(oopt)


On 05/03/2012 05:21 PM, David Rossiter wrote:
> I often want to display two or more maps of the same area, prepared with spplot, side-by-side, but the sizes of the map do not match if (1) a legend is printed and (2) the width of the text in the legend is different. For example:
> 
>> require(gstat)
>> data(jura)
>> coordinates(jura.grid) <- ~ Xloc + Yloc
>> gridded(jura.grid) <- T
>>  fullgrid(jura.grid) <- T
>> print(, split=c(1,1,2,1), more=T)
>> p1 <- spplot(jura.grid, zcol="Landuse", col.regions=terrain.colors(4))
>> p2 <- spplot(jura.grid, zcol="Rock", col.regions=bpy.colors(5))
>> require(lattice)
>> print(p1, split=c(1,1,2,1), more=T)
>> print(p2, split=c(2,1,2,1), more=F)
> 
> Here, since the longest name of the rock types is longer than that of the landuse, the rock type map is smaller, to make room within the box for the legend.
> 
> (The same hapens if plotting kriging predictions next to their variances, if the numeric precision is not the same.)
> 
> I can get around the problem by adjusting the position within the box for the larger map:
> 
> print(p1, position=c(0.04,0.04,.96,.96), …)
> 
> but this (1) requires a manual assessment (maybe I could do it automatically by looking at the legend categories?) and (2) seems a clumsy way to do this. I have waded through the
> 
> I've tried to use the panel.height and panel.width arguments to print.trellis, but without success:
> 
>> str(p.width <- lattice.getOption("layout.widths")$panel)
> List of 3
>  $ x    : num 1
>  $ units: chr "null"
>  $ data : NULL
>> p.width <- list(0.9,"null",NULL)
> 
> But this (1) does not seem to affect the plots, (2) would probably only affect the whole panel, not just the map. I need to set the size of the map and legend separately.
> 
> I tried to present these as side-by-side levelplots, but since the levels are not the same this fails also:
> 
>> p3 <- spplot(jura.grid[c("Landuse","Rock")])
> Error in stack.SpatialPointsDataFrame(as(data, "SpatialPointsDataFrame"),  :
>   all factors should have identical levels
> 
> Thanks for any help,
> 
> D G Rossiter
> Senior University Lecturer
> Faculty of Geoinformation and Earth   Observation Science
> Universiteit Twente.
> Enschede (NL)
> 
> 
> Faculty of Geo-Information Science and Earth Observation (ITC)
> University of Twente
> Chamber of Commerce: 501305360000
> 
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-- 
Edzer Pebesma
Institute for Geoinformatics (ifgi), University of Münster
Weseler Straße 253, 48151 Münster, Germany. Phone: +49 251
8333081, Fax: +49 251 8339763  http://ifgi.uni-muenster.de
http://www.52north.org/geostatistics      e.pebesma at wwu.de