fix #27

traffic/core/flight.py

@@ -292,7 +292,10 @@ def callsign(self) -> Union[str, Set[str], None]:
         may be associated with the registration of an aircraft, its mission or
         with a route for a commercial aircraft.
         """
-        return self._get_unique("callsign")
+        callsign = self._get_unique("callsign")
+        if callsign != callsign:
+            raise ValueError("NaN appearing in callsign field")
+        return callsign
 
     @property
     def number(self) -> Union[str, Set[str], None]:
@@ -389,7 +392,10 @@ def icao24(self) -> Union[str, Set[str], None]:
 
         For example icao24 code 'ac82ec' is associated to 'N905NA'.
         """
-        return self._get_unique("icao24")
+        icao24 = self._get_unique("icao24")
+        if icao24 != icao24:
+            raise ValueError("NaN appearing in icao24 field")
+        return icao24
 
     @property
     def registration(self) -> Optional[str]:

traffic/data/adsb/opensky_impala.py

@@ -108,7 +108,7 @@ def _read_cache(cachename: Path) -> Optional[pd.DataFrame]:
             if count > 0:
                 s.seek(0)
                 # otherwise pandas would parse 1234e5 as 123400000.0
-                df = pd.read_csv(s, dtype={"icao24": str})
+                df = pd.read_csv(s, dtype={"icao24": str, "callsign": str})
                 if df.shape[0] > 0:
                     return df
 
@@ -382,7 +382,13 @@ def history(
                 continue
 
             df = self._format_history(df)
+
+            if "last_position" in df.columns:
+                if df.query("last_position == last_position").shape[0] == 0:
+                    continue
+
             df = self._format_dataframe(df)
+
             cumul.append(df)
 
         if len(cumul) == 0: