How do I read/work with PolyLineZM with maptools/sp?

Edzer:

Thank you for your suggestions, but it doesn't help much. It does not 
recover either Z or M as attributes or anyhow else.
The Z is dropped for SpatialPolygons and SpatialLines everywhere. The M is 
not a standard part of the specification - it isn't obvious what it should 
be. You'd need to rewrite the C code in shapelib for maptools or rgdal to 
access these, and create a 4D object. Alternatively, try anything perhaps 
in Python with OGR to dump 3D points with M as an attribute, and a 
grouping factor to point to the feature ID in the DBF file.

Roger

p <- as(s, "SpatialPointsDataFrame")
names(p)
[1] "Id"       "Lines.NR" "Lines.ID" "Line.NR" 
slotNames(p)
[1] "data"        "coords.nrs"  "coords"      "bbox"        "proj4string"
head(p at coords)
    coords.x1 coords.x2
[1,]  408794.5   4893921
[2,]  409088.3   4893599
[3,]  409165.2   4893484
[4,]  409434.7   4893214
[5,]  409684.9   4893060
[6,]  409742.6   4893060
head(p at data)
   Id Lines.NR Lines.ID Line.NR
0    1        1        0       1
0.1  1        1        0       1
0.2  1        1        0       1
0.3  1        1        0       1
0.4  1        1        0       1
0.5  1        1        0       1 
p$Z
NULL
p$z
NULL

I double checked that I'm working with correct shapefile that has Z values.

Mikhail

-----Original Message-----
From: Edzer Pebesma [mailto:edzer.pebesma at uni-muenster.de]
Sent: Monday, May 16, 2011 1:29 PM
To: Mikhail Titov
Cc: r-sig-geo at r-project.org
Subject: Re: [R-sig-Geo] How do I read/work with PolyLineZM with
maptools/sp?

On 05/16/2011 08:22 PM, Mikhail Titov wrote:
I would try s$M and s$Z to access M and Z when they are attributes.
But what do I do when they are not? It can work for points, but not a
line as I can't have attributes for individual points of a line. I would
prefer not to do any extra conversions in GIS before using R.

as(s, "SpatialPointsDataFrame")

Do I get it right that for now it is better to stick with shapefiles to
read PolylineZM?
Mikhail

--
Edzer Pebesma
Institute for Geoinformatics (ifgi), University of M?nster
Weseler Stra?e 253, 48151 M?nster, Germany. Phone: +49 251
8333081, Fax: +49 251 8339763  http://ifgi.uni-muenster.de
http://www.52north.org/geostatistics      e.pebesma at wwu.de

_______________________________________________
R-sig-Geo mailing list
R-sig-Geo at r-project.org
https://stat.ethz.ch/mailman/listinfo/r-sig-geo

Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no

How do I read/work with PolyLineZM with maptools/sp?

Thread (8 messages)