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I am trying to get raster to shape form in R using John Baumgartner's code. This function needs gdal_polygonize.py from gdal package. I installed gdal package using: (I am using MacOS Sierra Version 10.12.6)

brew install gdal --HEAD 

When I check for the version. It seems I have installed GDAL:

gdalinfo --version
GDAL 2.3.0dev, released 2017/99/99

Now when I try to run the gdal_polygoniseR function. It gives error. It needs gdal_polygonize.py file. I am stuck at this point:

> system.time(p <- gdal_polygonizeR(r1))
Error in gdal_polygonizeR(r1) : 
Can't find gdal_polygonize.py on your system.

I wanted to check if it exists or not and if it does then its path:

> Sys.which("gdal_polygonize.py")
gdal_polygonize.py 
            "" 

I saw that there is one additional step after installing GDAL:

echo 'export PATH=/Library/Frameworks/GDAL.framework/Programs:$PATH' >> ~/.bash_profile
source ~/.bash_profile

I am able to run this line but does not help as the framework folder does not have gdal folder. When I check for this I do not see "GDAL.framework" in my "Library/Frameworks/..".

If I am able to locate the ".py" file. I will be able to run the function.

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You have a problem with the unix paths in Mac OS X (see GDAL: Building On Mac)

1) The GDAL pre-compiled binaries of Kyng Chaos use the Framework way (installed in /Library/Frameworks/GDAL.framework).

Control

 $ /Library/Frameworks/GDAL.framework/Versions/2.2/unix/bin/gdal-config --libs
-L/Library/Frameworks/GDAL.framework/Versions/1.11/unix/lib -lgdal
 $ /Library/Frameworks/GDAL.framework/Versions/2.2/unix/bin/gdal-config --cflags
-I/Library/Frameworks/GDAL.framework/Versions/1.11/Headers2 

2) The Homebrew way installs all in /usr/local/Cellar/ with symbolic links in /usr/local/bin/

Control

$ gdal-config --libs
-L/usr/local/Cellar/gdal2/2.2/lib -lgdal
$ gdal-config --cflags
-I/usr/local/Cellar/gdal2/2.2/include

So, if you have installed only the Homebrew version, it is normal that

I do not see "GDAL.framework" in my "Library/Frameworks/..".

And there's no need to add /Library/Frameworks/GDAL.framework/Programs to your PATH

3) Now to find the gdal_polygonize.py file, simply use in the terminal

locate gdal_polygonize.py
  • This is helpful. Though locate command does not work for Mac OS. mdfind gdal_polygonize.py did the job for me. The function gives me another error from osgeo import gdal ModuleNotFoundError: No module named 'osgeo' Error in ogrInfo(dsn = dsn, layer = layer, encoding = encoding, use_iconv = use_iconv, : Cannot open data source. I hope to find some solution for this as well. – vikram Jun 3 '18 at 18:15

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