xarray 0.19 compatibility (#158)

doc/release_notes.rst

@@ -66,6 +66,7 @@ Future release
 * The share of shipping transformed into hydrogen fuel cell can be now defined for different years in the ``config.yaml`` file. The carbon emission from the remaining share is treated as a negative load on the atmospheric carbon dioxide bus, just like aviation and land transport emissions.
 * The transformation of the Steel and Aluminium production can be now defined for different years in the ``config.yaml`` file.
 * Include the option to alter the maximum energy capacity of a store via the ``carrier+factor`` in the ``{sector_opts}`` wildcard. This can be useful for sensitivity analyses. Example: ``co2 stored+e2`` multiplies the ``e_nom_max`` by factor 2. In this example, ``e_nom_max`` represents the CO2 sequestration potential in Europe.
+* Compatibility with ``xarray`` version 0.19.
 
 PyPSA-Eur-Sec 0.5.0 (21st May 2021)
 ===================================

scripts/build_population_layouts.py

@@ -90,8 +90,8 @@
 
     for key, pop in pop_cells.items():
 
-        ycoords = ('y', cutout.coords['y'])
-        xcoords = ('x', cutout.coords['x'])
+        ycoords = ('y', cutout.coords['y'].data)
+        xcoords = ('x', cutout.coords['x'].data)
         values = pop.values.reshape(cutout.shape)
         layout = xr.DataArray(values, [ycoords, xcoords])