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Dear Michael, For the moment, I found my way with a call to gzip through shell(cmd=paste("C:/gzip -d ", filename, ".gz", sep="")) after installing GZIP.exe at the root of C: I wasn't able to find the option allowing to keep the original .gz which is otherwise trashed but it is a minor problem for the moment. I will also have a look at the osgeo pages you adviced cause this might be a powerful and useful tool. Best regards Alex Michael Sumner a écrit : gzfile gives a connection, which readGDAL does not support - you need an actual dataset name that GDAL can understand (not necessarily just a file path btw).I think you will have to extract the tif with shell/system calls to gzip or similar - what OS are you using? Rtools provides a handy gzip that could be used if your system doesn't already have it (e.g. Windows). There are virtual drivers in GDAL for reading from compressed files (similar to the R gzfile connection mechanism), but it will depend on the installation of GDAL that you have with rgdal: http://trac.osgeo.org/gdal/wiki/UserDocs/ReadInZip http://osgeo-org.1803224.n2.nabble.com/Support-for-reading-GDAL-datasets-in-compressed-archives-gz-and-zip-td2035285.html It's not available on my system as far as I know ( or I'm not using it correctly) - if it were avaible in the GDAL used to build rgdal it should allow readGDAL to read from the "/vsigzip/path....gz" string. Cheers, Mike. On Fri, Jun 4, 2010 at 10:40 PM, Alexandre VILLERS <alexandre.vill...@cebc.cnrs.fr> wrote:Good afternoon, I know this not the most appropriate place to post this message but I hope that some of you have already been confronted to the same problem. I have a lot of NDVI tiff files that have been compressed with gzip (filename such as 81jul15a.n07-VIg_data.tif.gz ) and that I need to geoprocess with R. I would like to unzip the tif from within R but was not able to properly understand how to connect to the gz file and unzip it with this with function gzfile. Anybody with some lines of codes hanging that would save my afternoon (and help me understand how the connection works) ? Best regards and thanks for any help. Alex -- Alexandre Villers PhD. AgriPop Centre d'Etudes Biologiques de Chizé-CNRS UPR1934 79360 Beauvoir sur Niort Phone +33 (0)5 49 09 96 13 Fax +33 (0)5 49 09 65 26 __________ Information from ESET Mail Security, version of virus signature database 5171 (20100604) __________ The message was checked by ESET Mail Security. http://www.eset.com _______________________________________________ R-sig-Geo mailing list R-sig-Geo@stat.math.ethz.ch https://stat.ethz.ch/mailman/listinfo/r-sig-geo__________ Information from ESET Mail Security, version of virus signature database 5172 (20100604) __________ The message was checked by ESET Mail Security. http://www.eset.com -- Alexandre Villers PhD. AgriPop Centre d'Etudes Biologiques de Chizé-CNRS UPR1934 79360 Beauvoir sur Niort Phone +33 (0)5 49 09 96 13 Fax +33 (0)5 49 09 65 26 __________ Information from ESET Mail Security, version of virus signature database 5172 (20100604) __________ The message was checked by ESET Mail Security. http://www.eset.com |
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