Hi,
I am working on a library of map functions for R and I have started
with code to read shapefiles (the format is not great but it is ubiquitous).
I am not a windows person, but where I am working I don't have access to
any UNIX machines easily. So here's the problem I wrote C code to read
the information out of the shapefile header and I compiled it using
the script given in Ripley and Veneables programming compliments for
Cygwin tools. It seemed to work, however when I tried calling it from R
it didn't work (couldn't find the symbol).
here's what happend
> version
_
platform Windows
arch x86
os Win32
system x86, Win32
status
status.rev 0
major 0
minor 64.2
year 1999
month July
day 3
language R > dyn.load("D:/Nicholas/shapelib-1.2.5/Sshpopen.dll")
> read.shape("D:\Nicholas\jstuff\Geotools\examples\publands")
Error in .C("SHPOpen", as.character(shpname), as.character(shxname),
as.character(access), : C/Fortran function not in load
table> is.loaded(symbol.C("SHPOpen"))
[1] FALSE>
Am I doing something wrong when building the dll? here are the steps I used
gcc -mno-cygwin -O2 -c Sshpopen.c
echo LIBRARY Sshpopen > Sshpopen.def
echo EXPORTS >> Sshpopen.def
nm Sshpopen.o | \
sed -n "/^........ [BCDRT] _/s/^........ [BCDRT] _/ /p"
\>> Sshpopen.def
gcc -mno-cygwin -mdll -Wl,--base-file,Sshpopen.b \
-o Sshpopen.dll Sshpopen.o
dlltool -k -D Sshpopen.dll -b Sshpopen.b -e Sshpopen.e -d Sshpopen.def
gcc -mno-cygwin -mdll -Wl,--base-file,Sshpopen.b \
-o Sshpopen.dll Sshpopen.e Sshpopen.o
dlltool -k -D Sshpopen.dll -b Sshpopen.b -e Sshpopen.e -d Sshpopen.def
gcc -mno-cygwin -mdll -o Sshpopen.dll Sshpopen.e Sshpopen.o
rm -f Sshpopen.b Sshpopen.e
Thanks for any insight
Nicholas
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