problems loading spproj library for transform()

thanks for the prompt reply

the method spTransform() worked

I now have an attribute file of class SpatiaPointsDataFrame with EM38
readings.  I also have a separate shape file of class
SpatialPolygonsDataFrame which I imported form an ESRI shape file using the
readOGR() method of rgdal.  I would like to superpose the two files in a
plot but so far have not been successful in lining them up satisfactorily.
I am not sure if the misalignement is due to my misguided plotting method

p1 <- spplot(x, c("var"))  #attribute data
p2 <- spplot (x2)  # shapefile

print(p1, split = c(1,1,1,1), more = TRUE)
print(p2, split = c(1,1,1,1), more = FALSE)
Th spplot() methods use lattice graphics, so I am not confident that you 
can validly overplot. Can you try first with base graphics, possibly using 
xlim= and ylim= to zoom in and locator() to check coordinates? 

Shapefiles do not themselves have projection information, it is in a 
separate *.prj file. If you don't have one, you may need to establish it 
yourself. It is not used for plotting Spatial* objects beyond 
conditionally stretching the y axis aspect when is.projected() is TRUE. If 
the objects have been created by spTransform(), the projection information 
has been set, and can be accessed by proj4string().

Roger
or due to the fact that the projections of the two files differ.  I am not
sure how to extract projection information from the shape file.

any hints would be appreciated

Karl

|---------+----------------------------------->
|         |           Roger.Bivand at nhh.no     |
|         |           Sent by:                |
|         |           r-sig-geo-bounces at stat.m|
|         |           ath.ethz.ch             |
|         |                                   |
|         |                                   |
|         |           25/05/2006 15:41        |
|         |           Please respond to       |
|         |           Roger.Bivand            |
|         |                                   |
|---------+----------------------------------->
  >------------------------------------------------------------------------------------------------------------------------------|
  |                                                                                                                              |
  |       To:       mdsumner at utas.edu.au                                                                                         |
  |       cc:       r-sig-geo at stat.math.ethz.ch                                                                                  |
  |       Subject:  Re: [R-sig-Geo] problems loading spproj library for transform()                                              |
  >------------------------------------------------------------------------------------------------------------------------------|

On Thu, 25 May 2006, Michael Sumner wrote:

Hello

I have the same problem, I've been meaning to explore further before
posting, but since spproj is not on CRAN I don't think I've missed
something obvious. This seems to be related to rgdal 0.4-4:

In rgdal, try running example("spTransform-methods") - if it works, use
spTransform() instead of transform().

Sorry for the muddle.

Roger

## using data from ?project example

library(rgdal)

## project works OK
  data(state)
  res <- project(cbind(state.center$x, state.center$y), "+proj=lcc
+lat_1=48 +lat_2=33 +lon_0=-100")
  res1 <- project(res, "+proj=lcc +lat_1=48 +lat_2=33 +lon_0=-100",
inv=TRUE)

## but transform does not

res <- SpatialPoints(res, CRS("+proj=lcc +lat_1=48 +lat_2=33 +lon_0
=-100"))
sessionInfo()
#Version 2.3.0 (2006-04-24)
#i386-pc-mingw32

#attached base packages:
#[1] "methods"   "stats"     "graphics"  "grDevices" "utils"
"datasets"
#[7] "base"

#other attached packages:
#   rgdal   pixmap    abind       sp
# "0.4-4"  "0.4-4"  "1.1-0" "0.8-14"

transform(res, CRS("+proj=longlat"))
#Loading required package: spproj
#Error in transform(res, CRS("+proj=longlat")) :
#        for using (coordinate) transform on objects deriving from
Spatial, library spproj is required
#In addition: Warning message:
#there is no package called 'spproj' in: library(package, lib.loc =
lib.loc, character.only = TRUE, logical = TRUE,

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--
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

_______________________________________________
R-sig-Geo mailing list
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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

problems loading spproj library for transform()

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