simplify navdata.pandas_df() to allow it to work with empty NavData structures

Author: betaBison

gnss_lib_py/parsers/navdata.py

@@ -154,15 +154,16 @@ def pandas_df(self):
         df : pd.DataFrame
             DataFrame with data, including strings as strings
         """
+
         df_list = []
-        for key, value in self.str_map.items():
-            if value:
-                vect_val = self.get_strings(key)
-            else:
-                vect_val = self.array[self.map[key], :]
-            df_val = pd.DataFrame(vect_val, columns=[key])
-            df_list.append(df_val)
-        dframe = pd.concat(df_list, axis=1)
+        for row in self.rows:
+            df_list.append(np.atleast_1d(self[row]))
+
+        # transpose list to conform to Pandas input
+        df_list = [list(x) for x in zip(*df_list)]
+
+        dframe = pd.DataFrame(df_list,columns=self.rows)
+
         return dframe
 
     def get_strings(self, key):

tests/parsers/test_navdata.py

@@ -148,6 +148,13 @@ def fixture_df_int_first(csv_int_first):
     """
     return load_test_dataframe(csv_int_first)
 
+@pytest.fixture(name='df_only_header')
+def fixture_df_only_header(csv_only_header):
+    """df where only headers given and no data.
+
+    """
+    return load_test_dataframe(csv_only_header)
+
 @pytest.fixture(name="data")
 def load_test_navdata(df_simple):
     """Creates a NavData instance from df_simple.
@@ -1716,3 +1723,40 @@ def test_in_rows_multi(data):
                 data_temp.in_rows(combo_rows)
             for row in combo_rows:
                 assert row in str(excinfo.value)
+
+def test_pandas_df(df_simple, df_only_header):
+    """Test that the NavData class can be printed without errors
+
+    Parameters
+    ----------
+    df_simple : pd.DataFrame
+        Dataframe with which to construct NavData instance
+    df_only_header : pd.DataFrame
+        Dataframe with only column names and no data
+    """
+    navdata = NavData(pandas_df=df_simple)
+
+    # test simple DataFrame
+    pd.testing.assert_frame_equal(navdata.pandas_df().sort_index(axis=1),
+                                  df_simple.sort_index(axis=1),
+                                  check_names=True, check_dtype=False)
+
+    # test DataFrame with a single row of data
+    df_super_simple = pd.DataFrame([["first",1.,3,"fourth"]],
+                                    columns=["A","B","C","D"])
+    navdata = NavData(pandas_df=df_super_simple)
+    pd.testing.assert_frame_equal(navdata.pandas_df().sort_index(axis=1),
+                                  df_super_simple.sort_index(axis=1),
+                                  check_names=True, check_dtype=False)
+
+    # make sure print doesn't break if given only headers
+    navdata = NavData(pandas_df=df_only_header)
+    pd.testing.assert_frame_equal(navdata.pandas_df().sort_index(axis=1),
+                                  df_only_header.sort_index(axis=1),
+                                  check_names=True)
+
+    # make sure it doesn't break with empty NavData
+    navdata = NavData()
+    pd.testing.assert_frame_equal(navdata.pandas_df().sort_index(axis=1),
+                                  pd.DataFrame().sort_index(axis=1),
+                                  check_names=True)