Bugfix/ufrm missing lucodes

HISTORY.rst

@@ -58,6 +58,10 @@ Unreleased Changes
 * Crop Production Regression
     * Corrected a misspelled column name. The fertilization rate table column
       must now be named ``phosphorus_rate``, not ``phosphorous_rate``.
+* Urban Flood Risk
+    * Fixed a bug where lucodes present in the LULC raster but missing from
+      the biophysical table would either raise a cryptic IndexError or silently
+      apply invalid curve numbers. Now a helpful ValueError is raised.
 
 3.9.1 (2021-09-22)
 ------------------

src/natcap/invest/urban_flood_risk_mitigation.py

@@ -773,8 +773,30 @@ def _lu_to_cn_op(
     # pixel and the rows are the curve number index for the landcover
     # type under that pixel (0..3 are CN_A..CN_D and 4 is "unknown")
     valid_lucodes = lucode_array[valid_mask].astype(int)
+
+    try:
+        cn_matrix = lucode_to_cn_table[valid_lucodes]
+    except IndexError:
+        # Find the code that raised the IndexError, and possibly
+        # any others that also would have.
+        lucodes = numpy.unique(valid_lucodes)
+        missing_codes = lucodes[lucodes >= lucode_to_cn_table.shape[0]]
+        raise ValueError(
+            f'The biophysical table is missing a row for lucode(s) '
+            f'{missing_codes.tolist()}')
+
+    # Even without an IndexError, still must guard against
+    # lucodes that can index into the sparse matrix but were
+    # missing from the biophysical table. They have rows of all 0.
+    if not cn_matrix.sum(1).all():
+        empty_rows = numpy.where(lucode_to_cn_table.sum(1) == 0)
+        missing_codes = numpy.intersect1d(valid_lucodes, empty_rows)
+        raise ValueError(
+            f'The biophysical table is missing a row for lucode(s) '
+            f'{missing_codes.tolist()}')
+
     per_pixel_cn_array = (
-        lucode_to_cn_table[valid_lucodes].toarray().reshape(
+        cn_matrix.toarray().reshape(
             (-1, 4))).transpose()
 
     # this is the soil type array with values ranging from 0..4 that will

tests/test_ufrm.py

@@ -149,10 +149,53 @@ def test_ufrm_value_error_on_bad_soil(self):
 
         with self.assertRaises(ValueError) as cm:
             urban_flood_risk_mitigation.execute(args)
-            actual_message = str(cm.exception)
-            expected_message = (
-                'Check that the Soil Group raster does not contain')
-            self.assertTrue(expected_message in actual_message)
+
+        actual_message = str(cm.exception)
+        expected_message = (
+            'Check that the Soil Group raster does not contain')
+        self.assertTrue(expected_message in actual_message)
+
+    def test_ufrm_value_error_on_bad_lucode(self):
+        """UFRM: assert exception on missing lucodes."""
+        import pandas
+        from natcap.invest import urban_flood_risk_mitigation
+        args = self._make_args()
+
+        bad_cn_table_path = os.path.join(
+            self.workspace_dir, 'bad_cn_table.csv')
+        cn_table = pandas.read_csv(args['curve_number_table_path'])
+
+        # drop a row with an lucode known to exist in lulc raster
+        # This is a code that will successfully index into the
+        # CN table sparse matrix, but will not return valid data.
+        bad_cn_table = cn_table[cn_table['lucode'] != 0]
+        bad_cn_table.to_csv(bad_cn_table_path, index=False)
+        args['curve_number_table_path'] = bad_cn_table_path
+
+        with self.assertRaises(ValueError) as cm:
+            urban_flood_risk_mitigation.execute(args)
+
+        actual_message = str(cm.exception)
+        expected_message = (
+            f'The biophysical table is missing a row for lucode(s) {[0]}')
+        self.assertEqual(expected_message, actual_message)
+
+        # drop rows with lucodes known to exist in lulc raster
+        # These are codes that will raise an IndexError on
+        # indexing into the CN table sparse matrix. The test
+        # LULC raster has values from 0 to 21.
+        bad_cn_table = cn_table[cn_table['lucode'] < 15]
+        bad_cn_table.to_csv(bad_cn_table_path, index=False)
+        args['curve_number_table_path'] = bad_cn_table_path
+
+        with self.assertRaises(ValueError) as cm:
+            urban_flood_risk_mitigation.execute(args)
+
+        actual_message = str(cm.exception)
+        expected_message = (
+            f'The biophysical table is missing a row for lucode(s) '
+            f'{[16, 17, 18, 21]}')
+        self.assertEqual(expected_message, actual_message)
 
     def test_ufrm_string_damage_to_infrastructure(self):
         """UFRM: handle str(int) structure indices.