handle empty measurements in solve_wls

Author: betaBison

gnss_lib_py/algorithms/snapshot.py

@@ -35,7 +35,8 @@ def solve_wls(measurements, weight_type = None, only_bias = False,
     Parameters
     ----------
     measurements : gnss_lib_py.parsers.navdata.NavData
-        Instance of the NavData class
+        Instance of the NavData class which must include at least
+        ``gps_millis``, ``x_sv_m``, ``y_sv_m``, and ``z_sv_m``
     weight_type : string
         Must either be None or the name of a row in measurements
     only_bias : bool
@@ -132,7 +133,7 @@ def solve_wls(measurements, weight_type = None, only_bias = False,
             states.append([timestamp, np.nan, np.nan, np.nan, np.nan])
 
     if len(states) == 0:
-        states = [[np.nan]*5]
+        states = np.empty((0,5))
     states = np.array(states)
 
     state_estimate = NavData()

tests/algorithms/test_snapshot.py

@@ -646,3 +646,23 @@ def test_rotation_of_earth_fix(derived_2022):
         error_rotn = np.mean(np.abs(google_wls[idx, :] - glp_wls[idx, :]))
         error_no_rotn = np.mean(np.abs(google_wls[idx, :] - glp_wls_no_rotn[idx, :]))
         assert error_rotn < error_no_rotn
+
+def test_solve_wls_empty():
+    """Test scenario where an empty measurement class is passed in.
+
+    """
+
+    measurements = NavData()
+    measurements["gps_millis"] = []
+    measurements["x_sv_m"] = []
+    measurements["y_sv_m"] = []
+    measurements["z_sv_m"] = []
+    with pytest.warns(RuntimeWarning) as warns:
+        state_estimate = solve_wls(measurements)
+
+    # should have the following contents
+    assert "gps_millis" in state_estimate.rows
+    assert "x_rx_wls_m" in state_estimate.rows
+    assert "y_rx_wls_m" in state_estimate.rows
+    assert "z_rx_wls_m" in state_estimate.rows
+    assert "b_rx_wls_m" in state_estimate.rows