exposures: appropriate error message in latitude/longitude properties (#982)

* exposures: appropriate error message in latitude/longitude

* Update test_base.py

fix typo

* typo

* add hint to error message

Co-authored-by: Chahan M. Kropf <[email protected]>

* add hint to error message

Co-authored-by: Chahan M. Kropf <[email protected]>

* adjust test string and fix whitespace

---------

Co-authored-by: Chahan M. Kropf <[email protected]>

Author: emanuel-schmid

climada/entity/exposures/base.py

@@ -132,12 +132,40 @@ def gdf(self):
     @property
     def latitude(self):
         """Latitude array of exposures"""
-        return self.data.geometry.y.values
+        try:
+            return self.data.geometry.y.values
+        except ValueError as valerr:
+            nonpoints = list(
+                self.data[
+                    self.data.geometry.type != "Point"
+                ].geometry.type.drop_duplicates()
+            )
+            if nonpoints:
+                raise ValueError(
+                    "Can only calculate latitude from Points."
+                    f" GeoDataFrame contains {', '.join(nonpoints)}."
+                    " Please see the lines_polygons module tutorial."
+                ) from valerr
+            raise
 
     @property
     def longitude(self):
         """Longitude array of exposures"""
-        return self.data.geometry.x.values
+        try:
+            return self.data.geometry.x.values
+        except ValueError as valerr:
+            nonpoints = list(
+                self.data[
+                    self.data.geometry.type != "Point"
+                ].geometry.type.drop_duplicates()
+            )
+            if nonpoints:
+                raise ValueError(
+                    "Can only calculate longitude from Points."
+                    f" GeoDataFrame contains {', '.join(nonpoints)}."
+                    " Please see the lines_polygons module tutorial."
+                ) from valerr
+            raise
 
     @property
     def geometry(self):

climada/entity/exposures/test/test_base.py

@@ -27,7 +27,7 @@
 import rasterio
 import scipy as sp
 from rasterio.windows import Window
-from shapely.geometry import Point
+from shapely.geometry import MultiPolygon, Point, Polygon
 from sklearn.metrics import DistanceMetric
 
 import climada.util.coordinates as u_coord
@@ -652,6 +652,39 @@ def test_to_crs_epsg_crs(self):
             Exposures.to_crs(self, crs="GCS", epsg=26915)
         self.assertEqual("one of crs or epsg must be None", str(cm.exception))
 
+    def test_latlon_with_polygons(self):
+        """Check for proper error message if the data frame contains non-Point shapes"""
+        poly = Polygon(
+            [(10.0, 0.0), (10.0, 1.0), (11.0, 1.0), (11.0, 0.0), (10.0, 0.0)]
+        )
+        point = Point((1, -1))
+        multi = MultiPolygon(
+            [
+                (
+                    ((0.0, 0.0), (0.0, 1.0), (1.0, 1.0), (1.0, 0.0)),
+                    [((0.1, 1.1), (0.1, 1.2), (0.2, 1.2), (0.2, 1.1))],
+                )
+            ]
+        )
+        poly = Polygon()
+        exp = Exposures(geometry=[poly, point, multi, poly])
+        with self.assertRaises(ValueError) as valer:
+            exp.latitude
+        self.assertEqual(
+            "Can only calculate latitude from Points."
+            " GeoDataFrame contains Polygon, MultiPolygon."
+            " Please see the lines_polygons module tutorial.",
+            str(valer.exception),
+        )
+        with self.assertRaises(ValueError) as valer:
+            exp.longitude
+        self.assertEqual(
+            "Can only calculate longitude from Points."
+            " GeoDataFrame contains Polygon, MultiPolygon."
+            " Please see the lines_polygons module tutorial.",
+            str(valer.exception),
+        )
+
 
 class TestImpactFunctions(unittest.TestCase):
     """Test impact function handling"""