[R-sig-Geo] Using the Z value for 3-D polygons?

[Jim Burke]

Hi, I still need some help. Scant progress.

Resources: I have Deepayan's "Lattice" book and Roger,
Edzer, and Virgillio's "Applied Spatial Data Analysis"
if you want to refer me to anything there.

A. I use spplot with spplot.polygon parameters I receive the
   following error.
   . The argument seems there and returns "iso".
   . Am I missing something? My call is in section I below.
   "Error in append(list(formula, data = as(sdf, "data.frame"),
    aspect = aspect,: argument is missing, with no default"

B. By the way, mapasp doc could be cleaner. In the line below...
   1) no opening brace to match "180)" closing brace
   2) "middle of the map" the correct word is probably "median" not "mean"
    "let s = 1/cos(My * pi)/180) with My the y coordinate of the middle
    of the map (the mean of ylim)"

C. I would be happy to email my spatial polygon data frame if you want
   to experiment.

Below is my non working spplot call. Idea is to have a 3d version
that uses the z value.

I.  Errors with aspect function argument
    library(sp)
    library(maptools)  
    library(rgdal)     
    library(PBSmapping)
    tx3_sp <- readShapePoly("tx3_sp.shp", IDvar="PCT",
    proj4string=CRS("+proj=aea +ellps=GRS80 +datum=WGS84"))
 
    spplot (
        tx3_sp,                 # obj                      
        c("D_CNT"),             # zcol = names(obj). D_CNT has a max of 1693
        ,                       # other arguments passed to levelplot 
(grids,
                                # polygons) or xyplot (points)
        ,                       # names, to use in panel, if different 
from zcol
                                # names  
        scales = list(draw = FALSE), # scales argument to be passed to 
Lattice
                                     # plots;                              
        xlab = NULL,         
        ylab = NULL,         
        aspect = mapasp(obj,xlim,ylim),
                                 # aspect ratio for spatial axes; 
defaults to "iso"
                                 # (one unit on the x-axis equals one 
unit on the
                                 # y-axis) but may be set to more 
suitable values
                                 # if the data are e.g. if coordinates are
                                 #latitude/longitude                       
        panel = panel.polygonsplot,
                                 # depending on the class of obj, 
panel.polygonsplot
                                 # (for polygons or lines), 
panel.gridplot (grids) or
                                 # panel.pointsplot (points) is used; 
for further
                                 # control custom panel functions
                                 # can be supplied that call one of 
these panel functions,
                                 # but do read how the argument 
sp.layout may help
        sp.layout = NULL,        # NULL or list; see notes below
        ,                        # formula, optional; may be useful to 
plot a transformed
                                 # value. Defaults to z~x+y for single 
and z~x+y|name
                                 # for multiple attributes; use e.g. 
exp(x)~x+y|name to
                                 # plot the exponent of the 
z-variable                                
        xlim = bbox(tx3_sp)[1, ],# numeric; x-axis limits 
        ylim = bbox(tx3_sp)[2, ] # numeric; y-axis limits
        )

II.    > summary(tx3_sp)
       Object of class SpatialPolygonsDataFrame
       Coordinates:
            min     max
       r1 2488376 2542115
       r2 7003736 7046215
       Is projected: TRUE
       proj4string :
       [+proj=aea +ellps=GRS80 +datum=WGS84 +lat_1=29.5 +lat_2=45.5
       +towgs84=0,0,0]
       Data attributes: (I did not list these)

III.   mapasp(tx3_sp,bbox(tx3_sp)[1, ],bbox(tx3_sp)[2, ])
       [1] "iso"


Thanks,
Jim Burke


Jim Burke wrote:
> Hi Everyone,
>
> QUESTION: How can I plot a spatial polygon (SpatialPolygonsDataFrame) 
> as 3-d? Perhaps using "spplot.polygons" with its z value?
>
> GOAL: To have a series of polygons look like approximately like the 
> last example in the PDF below.
> http://ocw.mit.edu/NR/rdonlyres/Urban-Studies-and-Planning/11-521Spatial-Database-Management-and-Advanced-Geographic-Information-SystemsSpring2003/ACA80C9F-4089-403E-9669-50763381D08A/0/lect13c.pdf 
>
>
> EXAMPLE SUGGESTION: Use "spplot.pologons" with the venerable 
> SourceForge NC fig21.R example and using its color coding values as 
> the polygon $z value? Assuming lat and long are in the sp.
> http://r-spatial.sourceforge.net/gallery/#fig21.R
>
> Then if its not as straightforward as above, what would be the steps 
> to convert a spatial polygon to points or something to graph that way?
>
> Thanks,
> Jim Burke
>
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