I'm trying to calculate the area of US congressional districts (shapefiles from here). I have eight different district shapefiles. I can calculate areas perfectly for the first five shapefiles (corresponding to the 81st, 87th, 92nd, 93rd, and 98th Congresses).
But for the 103rd, 108th, and 113th Congress shapefiles, it screws up. When I calculate areas manually (Vector->Geometry Tools->Export/Add Geometry Columns), the progress bar stalls at some point (eg. 53% for districts113). When I calculate areas using python, (
processing.runalg('qgis:exportaddgeometrycolumns',layer,0,output)), I can see the progress bar slowly get up to 53%, then it finishes suddenly, and the resulting shapefile is missing half the states.
What's the problem here?