I asked a question earlier about how to invert my file
"hydropolys.shp" from a vector of ocean and seas to a vector of land and got sent to here, but I am experiencing issues where using the "Difference" tool, it returns an empty map.
So I tried to follow the instructions geoprocessing but this tool keeps giving the
"Not Responding" error. Any suggestions on what to do next? Or any other easy way to convert the shapefile? I am using QGIS 2.18. Or is there a way to do this instead in code in PyQGIS?