Handle scalar elevation values in nc_specs (#323)

* handle scalar elevation values in nc_specs * Update tests/test_utils.py --------- Co-authored-by: Trevor James Smith <[email protected]>
CSHS-CWRA · Dec 12, 2023 · 59ed853 · 59ed853
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diff --git a/HISTORY.rst b/HISTORY.rst
@@ -2,6 +2,11 @@
 History
 =======
 
+0.13 (unreleased)
+-----------------
+* Fixed problem with scalar elevation in netCDF files parsed with `nc_specs` (issue #279)
+
+
 0.12.3 (2023-10-02)
 -------------------
 * `RavenPy` now uses `platformdirs` to write `raven_testing` to the user's cache directory. Dynamic paths are now used to cache data dependent on the user's operating system. Developers can now safely delete the `.raven_testing_data` folder in their home directory without affecting the functionality of `RavenPy`.

diff --git a/ravenpy/config/utils.py b/ravenpy/config/utils.py
@@ -108,13 +108,17 @@ def nc_specs(
 
             try:
                 nc_elev = ds.cf["vertical"].name
-                attrs["elevation"] = ds.cf["vertical"][i]
             except KeyError:
                 nc_elev = "elevation" if "elevation" in ds else None
+
             finally:
                 if nc_elev is not None:
                     attrs["elevation_var_name_nc"] = nc_elev
-                    attrs["elevation"] = ds["elevation"][i]
+                    try:
+                        attrs["elevation"] = ds[nc_elev][i]
+                    except IndexError:
+                        # Elevation is a scalar
+                        attrs["elevation"] = ds[nc_elev].item(0)
 
             if "station_id" in ds:
                 if ds["station_id"].shape and len(ds["station_id"]) > i:

diff --git a/tests/conftest.py b/tests/conftest.py
@@ -219,6 +219,20 @@ def fit_params(ts_stats, tmp_path):
     return fn
 
 
+@pytest.fixture(scope="session")
+def bad_netcdf(salmon_meteo):
+    fn = salmon_meteo.parent / "bad_netcdf.nc"
+
+    if not fn.exists():
+        # Test with scalar elevation. Should normally have a station dimension, but not always the case.
+        ds = xr.open_dataset(salmon_meteo)
+        ds["station_name"] = ds["station_name"].astype("str")
+        ds["elevation"] = 1.0
+        ds.to_netcdf(fn)
+
+    return fn
+
+
 @pytest.fixture(scope="session")
 def salmon_hru():
     out = {}

diff --git a/tests/test_utils.py b/tests/test_utils.py
@@ -1,4 +1,5 @@
 import pytest
+import xarray as xr
 
 from ravenpy.config.utils import nc_specs
 
@@ -11,6 +12,12 @@ def test_nc_specs(get_local_testdata):
     assert "file_name_nc" in attrs
 
 
+def test_nc_specs_bad(bad_netcdf):
+    # Test with scalar elevation. Should normally have a station dimension, but not always the case.
+    attrs_s = nc_specs(bad_netcdf, "PRECIP", station_idx=1, alt_names=("rain",))
+    assert attrs_s["elevation"] == 1.0
+
+
 @pytest.mark.online
 def test_dap_specs():
     # Link to THREDDS Data Server netCDF testdata