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)

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()                                              |
  >------------------------------------------------------------------------------------------------------------------------------|

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

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