[R-sig-Geo] GDAL.close

[Roger Bivand]

On Wed, 6 Nov 2013, Oliver Soong wrote:

> That seems to have done it.  Thanks for your patience.

Good, thanks for checking. The bug fix will be in the next release of 
rgdal on CRAN.

Roger

>
> Oliver
>
>
> On Tue, Nov 5, 2013 at 11:50 AM, Roger Bivand <Roger.Bivand at nhh.no> wrote:
>
>> On Tue, 5 Nov 2013, Oliver Soong wrote:
>>
>>  Hi Roger,
>>>
>>> I forgot that RGDAL_CloseDataset nils dataset at handle, which means the
>>> subsequent RGDAL_CloseHandle can't find the handle to close.  It also
>>> means
>>> that GDAL.close should replace RGDAL_CloseDataset with RGDAL_CloseHandle.
>>> On linux, this will cause temporary datasets to be removed by the isTrans
>>> unlink code instead of GDALDeleteDataset, but it should make things work
>>> on
>>> Windows.  I don't know if there are drivers that might create files that
>>> don't match the unlink pattern.
>>>
>>> I do think it would be better to ultimately fix RGDAL_DeleteHandle.  Under
>>> normal circumstances, I would call RGDAL_CloseHandle (or equivalently call
>>> GDALClose and R_ClearExternalPtr directly) and then GDALDeleteDataset.
>>>  I'm
>>> still uncertain why the ordering is reversed or what the (commented out)
>>> #ifndef OSGEO4W deleteFile business is about.
>>>
>>
>> Thanks to Even Rouault on gdal-dev, I think that:
>>
>> http://win-builder.r-project.org/jJIzeDT1C100
>>
>> contains a fixed version, with RGDAL_DeleteHandle now closing the dataset
>> before deleting it. This worked on Linux and Windows in a rough cut, and
>> this one after removing the unneeded unlink() call in GDAL.close() now
>> works on Linux, and should also work on Windows. Behaviour on Linux and
>> Windows with respect to transient datasets being deleted is now the same.
>> It was helpful that you stayed with this, it was far from simple, as Even
>> explained on the gdal-dev thread.
>>
>> Roger
>>
>>
>>
>>> Cheers,
>>> Oliver
>>>
>>>
>>>
>>>
>>> On Tue, Nov 5, 2013 at 5:56 AM, Roger Bivand <Roger.Bivand at nhh.no> wrote:
>>>
>>>  On Tue, 5 Nov 2013, Oliver Soong wrote:
>>>>
>>>>  Hi Roger,
>>>>
>>>>>
>>>>> Toggling on GDALTransientDataset in GDAL.close doesn't change anything
>>>>> because RGDAL_CloseDataset already toggles on that.  In either case,
>>>>> RGDAL_DeleteHandle still doesn't work.  Also, the gc at the end doesn't
>>>>> do
>>>>> anything useful because .setCollectorFun has already trivialized the
>>>>> finalizer and because dataset still exists at that point, as does the
>>>>> source dataset given to GDAL.close in the first place.
>>>>>
>>>>> The HFA driver has the exact same issue.  From what I see in the code, I
>>>>> don't think it's related to the specific driver.
>>>>>
>>>>>
>>>> Here is the next version:
>>>>
>>>> http://win-builder.r-project.org/0X0318s8iW0C
>>>>
>>>> with:
>>>>
>>>>
>>>>             .setCollectorFun(slot(dataset, 'handle'), NULL)
>>>>             .Call('RGDAL_CloseDataset', dataset, PACKAGE="rgdal")
>>>>             .Call("RGDAL_CloseHandle", slot(dataset, 'handle'),
>>>>                 PACKAGE="rgdal")
>>>>
>>>> Running under Windows, and using:
>>>>
>>>> http://download.sysinternals.com/files/Handle.zip
>>>>
>>>> to check, the three transient datasets are open:
>>>>
>>>>   3B8: File  (RW-)   C:\Users\rsb\AppData\Local\
>>>> Temp\Rtmp8kZk0N\awlr2.tif
>>>>   3C0: File  (RW-)   C:\Users\rsb\AppData\Local\
>>>> Temp\Rtmp8kZk0N\tfur1.tif
>>>>   498: File  (RW-)   C:\Users\rsb\AppData\Local\
>>>> Temp\Rtmp8kZk0N\mxbr3.tif
>>>>
>>>> I'm assuming that RW- means read and write open, the third character is
>>>> D,
>>>> which is probably directory.
>>>>
>>>> Roger
>>>>
>>>>
>>>>
>>>>  Cheers,
>>>>> Oliver
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On Mon, Nov 4, 2013 at 3:05 PM, Oliver Soong <osoong+r at gmail.com>
>>>>> wrote:
>>>>>
>>>>>  Er, just saw your recent e-mail.  I'll take a look.
>>>>>
>>>>>>
>>>>>> Oliver
>>>>>>
>>>>>>
>>>>>> On Mon, Nov 4, 2013 at 3:05 PM, Oliver Soong <osoong+r at gmail.com>
>>>>>> wrote:
>>>>>>
>>>>>>  I do think we've gotten a bit muddled.  I'm probably not helping, but
>>>>>>
>>>>>>> I'll do my best.
>>>>>>>
>>>>>>> Windows XP (32-bit), 7 (32-bit), and 2008 R2 (32-bit and 64-bit),
>>>>>>> R-3.0.2, sp 1.0.13, rgdal 0.8.11, raster 2.1.49.
>>>>>>>
>>>>>>> The main problem as seen by end-users is the orphaned temporary files
>>>>>>> that you observed were left over for r1 and r2.  They cannot be
>>>>>>> removed
>>>>>>> while R is running.  I seem not to have explained r3 very well, but
>>>>>>> suffice
>>>>>>> it to say that GDAL.close(r3) creates similar orphaned temporary
>>>>>>> files,
>>>>>>> indicating GDAL.close is not functioning properly on
>>>>>>> GDALTransientDataset
>>>>>>> objects under Windows.
>>>>>>>
>>>>>>> I think RGDAL_DeleteHandle (and hence RGDAL_CloseDataset) is the root
>>>>>>> of
>>>>>>> the problem, and I think it's not properly closing the file handle
>>>>>>> before
>>>>>>> trying and failing to delete the associated files.  Windows
>>>>>>> automatically
>>>>>>> locks open file handles, but linux requires extra steps that are not
>>>>>>> always
>>>>>>> done and are not always respected, which is probably why this isn't
>>>>>>> apparent under linux.  The finalizer code and resetting seems
>>>>>>> appropriate.
>>>>>>>
>>>>>>> I still hesitate to say much about RGDAL_DeleteHandle, but I will
>>>>>>> point
>>>>>>> out that one is normally supposed to close the file handle before
>>>>>>> deleting
>>>>>>> the file, and it seems backwards in RGDAL_DeleteHandle.  I don't know
>>>>>>> if
>>>>>>> that is intentional.
>>>>>>>
>>>>>>> After thinking a little more, I think it's better to switch the calls
>>>>>>> to
>>>>>>> RGDAL_CloseHandle and RGDAL_CloseDataset that I suggested originally
>>>>>>> for
>>>>>>> GDAL.close.  That means simply adding the call to RGDAL_CloseHandle
>>>>>>> after
>>>>>>> the call to RGDAL_CloseDataset, rather than before.  With this code,
>>>>>>> if
>>>>>>> RGDAL_CloseDataset behaves as intended, RGDAL_CloseHandle will get a
>>>>>>> nil
>>>>>>> pointer and won't do anything.  However, if RGDAL_CloseDataset fails
>>>>>>> to
>>>>>>> function properly, RGDAL_CloseHandle will close the open handle and
>>>>>>> the
>>>>>>> if(isTrans) cleanup code already in GDAL.close will operate.
>>>>>>>
>>>>>>> Perhaps I could be more helpful if you explained what you thought my
>>>>>>> suggested change might break?  This last one (the existing
>>>>>>> RGDAL_CloseDataset followed by an additional RGDAL_CloseHandle) should
>>>>>>> be
>>>>>>> no worse than the current code.
>>>>>>>
>>>>>>> Is that at all clearer?
>>>>>>>
>>>>>>> Oliver
>>>>>>>
>>>>>>>
>>>>>>> On Mon, Nov 4, 2013 at 1:03 PM, Roger Bivand <Roger.Bivand at nhh.no>
>>>>>>> wrote:
>>>>>>>
>>>>>>>  Which Windows? XP, Vista, 7, 8, 8.1? 32 and 64 bit? If Vista/7/8, run
>>>>>>>
>>>>>>>> as
>>>>>>>> administrator or not? I agree that the code in those parts of rgdal
>>>>>>>> is
>>>>>>>> not
>>>>>>>> well-designed - it was well-designed, but has been modified so that
>>>>>>>> it
>>>>>>>> works for most people cross-platform, and has had to accommodate
>>>>>>>> changes
>>>>>>>> that have taken place in GDAL over more than 10 years, not least the
>>>>>>>> error-handler.
>>>>>>>>
>>>>>>>> The simple solution to your practical problem is to for you to use a
>>>>>>>> larger temporary drive under Windows, or change to an operating
>>>>>>>> system
>>>>>>>> that
>>>>>>>> does not have these side-effects.
>>>>>>>>
>>>>>>>> Assisting you is not just a matter of doing what you think works for
>>>>>>>> you, but making sure it doesn't break anything else for anybody else
>>>>>>>> cross-platform.
>>>>>>>>
>>>>>>>> Your script does not check for other files in tempdir, so I
>>>>>>>> prepended a
>>>>>>>> listing of prior content:
>>>>>>>>
>>>>>>>> pc <- dir(tempdir())
>>>>>>>>
>>>>>>>> and dropped them from the list for unlinking:
>>>>>>>>
>>>>>>>> now <- dir(tempdir())
>>>>>>>> unlink(paste(tempdir(), now[!(now %in% pc)], sep=.Platform$file.sep))
>>>>>>>>
>>>>>>>> I do not see how your script exercises the problem. It creates a new
>>>>>>>> transient file, but does not close it, which was the behaviour you
>>>>>>>> are
>>>>>>>> unhappy with. If I add
>>>>>>>>
>>>>>>>> GDAL.close(r3)
>>>>>>>>
>>>>>>>> on Linux, the transient dataset is removed. On Windows 7 64-bit with
>>>>>>>> the
>>>>>>>> CRAN rgdal binary run as user, temporary files are left in tempdir
>>>>>>>> for
>>>>>>>> r1,
>>>>>>>> r2, and r3. The same three temporary files are left when run as
>>>>>>>> administrator.
>>>>>>>>
>>>>>>>> The earliest version of GDAL.close was:
>>>>>>>>
>>>>>>>> GDAL.close <- function(dataset) {
>>>>>>>>             .setCollectorFun(slot(dataset, 'handle'), NULL)
>>>>>>>>             .Call('RGDAL_CloseDataset', dataset, PACKAGE="rgdal")
>>>>>>>>             invisible()
>>>>>>>> }
>>>>>>>>
>>>>>>>> with a version in 2007 in the THK branch calling a closeDataset
>>>>>>>> method,
>>>>>>>> containing:
>>>>>>>>
>>>>>>>>             handle <- slot(dataset, "handle")
>>>>>>>>             unreg.finalizer(handle)
>>>>>>>>             .Call("RGDAL_DeleteHandle", handle, PACKAGE="rgdal")
>>>>>>>>
>>>>>>>> with:
>>>>>>>>
>>>>>>>> unreg.finalizer <- function(obj) reg.finalizer(obj, function(x) x)
>>>>>>>>
>>>>>>>> and by 2010 was:
>>>>>>>>
>>>>>>>> GDAL.close <- function(dataset) {
>>>>>>>>             .setCollectorFun(slot(dataset, 'handle'), NULL)
>>>>>>>>             .Call('RGDAL_CloseDataset', dataset, PACKAGE="rgdal")
>>>>>>>>             invisible(gc())
>>>>>>>> }
>>>>>>>>
>>>>>>>> Special handling of GDALTransientDataset was added in revision 433 in
>>>>>>>> Janual 2013, and modified in revision 462 in April 2013.
>>>>>>>>
>>>>>>>> It has seemed IIRC that Windows can treat arbitrary files as open. It
>>>>>>>> is
>>>>>>>> also possible that there is an interaction between Windows and
>>>>>>>> rgdal:::.setCollectorFun(), which does what it should, when given the
>>>>>>>> NULL
>>>>>>>> argument, setting:
>>>>>>>>
>>>>>>>> .setCollectorFun <- function(object, fun) {
>>>>>>>>
>>>>>>>>   if (is.null(fun)) fun <- function(obj) obj
>>>>>>>>   reg.finalizer(object, fun, onexit=TRUE)
>>>>>>>>
>>>>>>>> }
>>>>>>>>
>>>>>>>> so incorporating the THK branch logic. It could possibly also vary
>>>>>>>> across drivers, so finding a robust fix means setting up a test rig
>>>>>>>> with
>>>>>>>> multiple Windows machines and testing for multiple drivers to see why
>>>>>>>> some
>>>>>>>> temprary files are being treated as open when other operating systems
>>>>>>>> don't
>>>>>>>> have problems in their removal. Windows users with too small
>>>>>>>> temporary
>>>>>>>> directories. I welcome contributions from people who understand
>>>>>>>> Windows and
>>>>>>>> can actually explain why we see the consequences we see.
>>>>>>>>
>>>>>>>> One candidate may be to branch to .Call("RGDAL_DeleteHandle", handle,
>>>>>>>> PACKAGE="rgdal") for the GDALTransientDataset case; I'll report back
>>>>>>>> once
>>>>>>>> the package has gone through win-builder.
>>>>>>>>
>>>>>>>> Hope this doesn't muddle too much, clarification doesn't seem like
>>>>>>>> the
>>>>>>>> right expression.
>>>>>>>>
>>>>>>>> Roger
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On Sun, 3 Nov 2013, Oliver Soong wrote:
>>>>>>>>
>>>>>>>>  I've been using the CRAN rgdal and raster.  I apologize in advance
>>>>>>>> for
>>>>>>>>
>>>>>>>>  all
>>>>>>>>> the linebreaks that will be broken.  This code should highlight the
>>>>>>>>> problem
>>>>>>>>> and the fix:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> require(rgdal)
>>>>>>>>> require(raster)
>>>>>>>>> r1 <- raster(system.file("external/test.grd", package="raster"))
>>>>>>>>> r2 <- as(r1, "SpatialGridDataFrame")
>>>>>>>>> r2.dims <- gridparameters(r2)$cells.dim
>>>>>>>>> r3 <- new("GDALTransientDataset", driver = new("GDALDriver",
>>>>>>>>> "GTiff"),
>>>>>>>>> rows
>>>>>>>>> = r2.dims[2], cols = r2.dims[1], bands = 1, type = "Float32",
>>>>>>>>> options
>>>>>>>>> =
>>>>>>>>> NULL, fname = file.path(tempdir(), "r3.tif"), handle = NULL)
>>>>>>>>> print(dir(tempdir()))
>>>>>>>>> writeRaster(r1, file.path(tempdir(), "r1.tif"))
>>>>>>>>> writeGDAL(r2, file.path(tempdir(), "r2.tif"))
>>>>>>>>> print(dir(tempdir()))
>>>>>>>>> unlink(dir(tempdir(), full.names = TRUE))
>>>>>>>>> print(dir(tempdir()))
>>>>>>>>> leftover <- gsub("/", "\\\\", dir(tempdir(), full.names = TRUE))
>>>>>>>>> invisible(lapply(paste("cmd /c del", leftover), system))
>>>>>>>>> rm(r1, r2, r3)
>>>>>>>>> gc()
>>>>>>>>> unlink(dir(tempdir(), full.names = TRUE))
>>>>>>>>> print(dir(tempdir()))
>>>>>>>>> invisible(lapply(paste("cmd /c del", leftover), system))
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Basically, I'm trying to write a standard raster package raster (r1)
>>>>>>>>> and an
>>>>>>>>> sp package SpatialGridDataFrame (r2).  Both of those end up calling
>>>>>>>>> new("GDALTransientDataset"), hence r3.  At the first
>>>>>>>>> print(dir(tempdir())),
>>>>>>>>> only r3 has an open temporary file, which is expected.  At the
>>>>>>>>> second,
>>>>>>>>> all
>>>>>>>>> three have open temporary files, and r1 and r2 have their written
>>>>>>>>> final
>>>>>>>>> outputs, which are closed.  The temporary files for r1 and r2 should
>>>>>>>>> have
>>>>>>>>> been closed at this point.  None of the temporary files can be
>>>>>>>>> removed
>>>>>>>>> by
>>>>>>>>> unlink, although the final outputs can, as shown at the third
>>>>>>>>> print(dir(tempdir())).  Windows can't remove them, either.  However,
>>>>>>>>> if
>>>>>>>>> I
>>>>>>>>> remove the GDALTransientDataset r3 and initiate gc(), R can remove
>>>>>>>>> that
>>>>>>>>> temporary file, but this does not work for r1 and r2.  After q(),
>>>>>>>>> the
>>>>>>>>> tempdir() will not be removed by R, but it and the temporary files
>>>>>>>>> for
>>>>>>>>> r1
>>>>>>>>> and r2 can now be removed.
>>>>>>>>>
>>>>>>>>> It looks like GDAL.close is broken (again/as always), but the
>>>>>>>>> collector
>>>>>>>>> function for GDALTransientDataset seems to at least close the
>>>>>>>>> handle.
>>>>>>>>> GDAL.close relies on RGDAL_CloseDataset, whereas the
>>>>>>>>> GDALTransientDataset
>>>>>>>>> collector just uses RGDAL_CloseHandle.  With the handle closed, I
>>>>>>>>> think
>>>>>>>>> the
>>>>>>>>> unlink code in GDAL.close will work (as an aside, I'd use the
>>>>>>>>> pattern
>>>>>>>>> paste0("^[a-z]{3}", basen, "$") to be safer and the argument
>>>>>>>>> full.names
>>>>>>>>> might be simpler than constructing flf separately).  I believe
>>>>>>>>> RGDAL_CloseDataset checks for NULL handles but just returns early,
>>>>>>>>> so
>>>>>>>>> it
>>>>>>>>> should be the same to replace the .Call("RGDAL_CloseDataset", ...)
>>>>>>>>> with
>>>>>>>>> .Call("RGDAL_CloseHandle", ...).
>>>>>>>>>
>>>>>>>>> Really, I think RGDAL_DeleteHandle needs to be fixed, but I don't
>>>>>>>>> know
>>>>>>>>> enough about GDALDeleteDataset or the #ifndef OSGEO4W deleteFile
>>>>>>>>> business
>>>>>>>>> or why RGDAL_CloseHandle is commented out to make any useful
>>>>>>>>> suggestions
>>>>>>>>> there.
>>>>>>>>>
>>>>>>>>> Cheers,
>>>>>>>>> Oliver
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Fri, Nov 1, 2013 at 1:41 AM, Roger Bivand <Roger.Bivand at nhh.no>
>>>>>>>>> wrote:
>>>>>>>>>
>>>>>>>>>  On Mon, 28 Oct 2013, Oliver Soong wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>>  I've had a long standing struggle with GDAL.close on Windows, and
>>>>>>>>>> I
>>>>>>>>>>
>>>>>>>>>>  think I might finally have found a fix.  I'm currently running
>>>>>>>>>> rgdal
>>>>>>>>>>
>>>>>>>>>>> 0.8.11, R 3.0.2, and 32-bit Windows 7.
>>>>>>>>>>>
>>>>>>>>>>> Currently, writeRaster and writeGDAL create temporary files in the
>>>>>>>>>>> tempdir() folder (the final filename prefixed with 3 random [a-z]
>>>>>>>>>>> letters).  On my system, these files get left open and orphaned.
>>>>>>>>>>>  When
>>>>>>>>>>> doing heavy processing, this can lead to the drive hosting the
>>>>>>>>>>> tempdir() folder to become full, even if the data is being
>>>>>>>>>>> ultimately
>>>>>>>>>>> written to a much larger drive.  This also means that R cannot
>>>>>>>>>>> clean
>>>>>>>>>>> up these files or the tempdir() folder when it closes, causing
>>>>>>>>>>> similar
>>>>>>>>>>> bloat in my %TEMP%.
>>>>>>>>>>>
>>>>>>>>>>> I haven't tested this on other platforms, but I think it might
>>>>>>>>>>> help
>>>>>>>>>>> to
>>>>>>>>>>> insert an extra line into GDAL.close:
>>>>>>>>>>>
>>>>>>>>>>> .setCollectorFun(slot(dataset, "handle"), NULL)
>>>>>>>>>>> .Call("RGDAL_CloseHandle", dataset at handle, PACKAGE = "rgdal")
>>>>>>>>>>> .Call("RGDAL_CloseDataset", dataset, PACKAGE = "rgdal")
>>>>>>>>>>>
>>>>>>>>>>> For whatever reason, RGDAL_CloseDataset doesn't seem to actually
>>>>>>>>>>> close
>>>>>>>>>>> the C file handle, but it doesn't seem to mind if the file handle
>>>>>>>>>>> was
>>>>>>>>>>> closed beforehand.
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>  Could you please provide a working example? I have looked at
>>>>>>>>>>> this,
>>>>>>>>>>>
>>>>>>>>>> but
>>>>>>>>>> need a baseline to know whether I'm looking at the same thing. I'm
>>>>>>>>>> very
>>>>>>>>>> unsure that this is a robust solution, and need an instrumented
>>>>>>>>>> example,
>>>>>>>>>> including listings of the temporary directory during the process,
>>>>>>>>>> to
>>>>>>>>>> see
>>>>>>>>>> the consequences. Thanks for looking into this, but I'd prefer to
>>>>>>>>>> be
>>>>>>>>>> sure
>>>>>>>>>> that a Windows-specific fix doesn't make things worse for others
>>>>>>>>>> too.
>>>>>>>>>> Please also report on the source of your Windows rgdal binary - is
>>>>>>>>>> it
>>>>>>>>>> from
>>>>>>>>>> CRAN or locally built dynamically linking your own GDAL?
>>>>>>>>>>
>>>>>>>>>> Best wishes,
>>>>>>>>>>
>>>>>>>>>> Roger
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>  Cheers,
>>>>>>>>>>
>>>>>>>>>>  Oliver
>>>>>>>>>>>
>>>>>>>>>>> _______________________________________________
>>>>>>>>>>> R-sig-Geo mailing list
>>>>>>>>>>> R-sig-Geo at r-project.org
>>>>>>>>>>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>  --
>>>>>>>>>>>
>>>>>>>>>>>  Roger Bivand
>>>>>>>>>> Department of Economics, NHH Norwegian School of Economics,
>>>>>>>>>> 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
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>   --
>>>>>>>>>
>>>>>>>> Roger Bivand
>>>>>>>> Department of Economics, NHH Norwegian School of Economics,
>>>>>>>> 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
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>  --
>>>> Roger Bivand
>>>> Department of Economics, NHH Norwegian School of Economics,
>>>> 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
>>>>
>>>>
>>>>
>>>
>> --
>> Roger Bivand
>> Department of Economics, NHH Norwegian School of Economics,
>> 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
>>
>>
>

-- 
Roger Bivand
Department of Economics, NHH Norwegian School of Economics,
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