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I'd like to run an R script on a layer loaded in QGIS (to rotate a set of points created there using the Vector:Research Tools:Regular Points tool). I thought ManageR might work but cannot get it working on OSX ...

Of course, I could do it manually (create layer -> run script from within R -> find output and reload into QGIS) but surely there is a more elegant solution?

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On OsX you will need the python rpy2 package (to run ManageR). The QGIS OsX packager said yesterday that it will add it to his downloads page. Check the QGIS/OsX download page in the next days. –  Giovanni Manghi Nov 23 '11 at 15:30
    
Nice - that will save a LOT of trouble! easy_install rpy2 worked for me, and my paths seem correct, but manageR still seems to fail with File "/Library/Python/2.7/site-packages/rpy2-2.2.2dev_20110903-py2.7-macosx-10.7-inte‌​l.egg/rpy2/rinterface/__init__.py", line 7, in R_HOME = tmp.readlines() IOError: [Errno 4] Interrupted system call –  Simbamangu Nov 23 '11 at 15:35
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2 Answers

Currently I can't get manageR working on a Linux box - there's a problem importing layers into R from Qgis. I had a chat to Carson Farmer (the one-man magic machine who wrote manageR) and he's aware of the problem and is going to take a look at it sometime.

If that's your manageR problem (you weren't specific - couldn't get it working or couldn't get it installed? A problem getting Rpy2 on Mac?) then you'll just have to wait for that fix, or dive into the python and fix it yourself.

Otherwise, if the layer is saved as a shapefile or other OGR/GDAL source you'll have to get it via rgdal:readOGR or maptools:readShapeSpatial from R. Not too inelegant, but the other option is writing a bunch of python code to dump the layer to something like that yourself - which is essentially what manageR is all about...

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ManageR fails to load ... at all ... giving errors that don't get fixed by any of the usual path fixes. rpy2 is installed just fine! I was hoping to avoid the 'write a bunch of python code' bit but that is starting to look like the best solution! Need to dive into it I guess (seems a bit less frightening now that I've worked out some R code). –  Simbamangu Nov 23 '11 at 13:42
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up vote 3 down vote accepted

It is possible to get manageR working on OSX (Lion 10.7.2) at least.

It looks like the problem with manageR / rpy2 was actually problems with the previous R builds (2.13 at least) - symlinks were referring to the wrong location.

  1. Update R to 2.14 (binary from r-project.org);
  2. Reinstall QGIS (Kyngchaos installer);
  3. Reinstall GDAL_complete (Kyngchaos again);
  4. Reinstall rpy2 (latter via pip), rebooted ...

... and manageR now loads and works. Haven't tried this in Linux yet.

UPDATE: The SEXTANTE plugin can be used to write scripts that call R, with some modifications in OSX to make it work properly.

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