FIX: incorrect quali session split; closes #605

fastf1/core.py

@@ -3340,13 +3340,32 @@ def split_qualifying_sessions(self) -> list[Optional["Laps"]]:
         # add the very last timestamp, to get an end for the last interval
         split_times.append(self.session.session_status['Time'].iloc[-1])
         laps = [None, None, None]
+        prev_early = None
         for i in range(len(split_times) - 1):
             # split by start time instead of end time, because the split times
             # that are generated from timing data may not account for crashed
             # cars being returned or having a generated lap time that results
             # in a late 'Time' value!
-            laps[i] = self[(self['LapStartTime'] > split_times[i])
-                           & (self['LapStartTime'] < split_times[i + 1])]
+            cond = ((self['LapStartTime'] > split_times[i])
+                    & (self['LapStartTime'] < split_times[i + 1]))
+
+            # if this is Q2 or Q3 and there are left over "early" laps from the
+            # last session, add them to the current session
+            if prev_early is not None:
+                cond |= prev_early
+
+            # find laps that "start" early, this happens when cars cross the
+            # timing beam in the pits before the next quali session starts:
+            # lap is pit out, starts in current session, ends in next session
+            is_early = ((self['LapStartTime'] < split_times[i + 1])
+                        & (self['Time'] > split_times[i + 1])
+                        & ~pd.isna(self['PitOutTime']))
+
+            # select the laps for the current session, excluding the early laps
+            laps[i] = self[cond & ~is_early]
+
+            prev_early = is_early
+
             if laps[i].empty:
                 laps[i] = None
         return laps

fastf1/tests/test_laps.py

@@ -286,7 +286,7 @@ def test_laps_pick_track_status(reference_laps_data):
 @pytest.mark.f1telapi
 @pytest.mark.parametrize("source", ["session_status", "timing_data"])
 def test_split_quali_laps(source):
-    session = fastf1.get_session(2023, 2, 'Q')
+    session = fastf1.get_session(2024, 10, 'Q')
     session.load(telemetry=False, weather=False)
 
     if source == "session_status":
@@ -295,10 +295,17 @@ def test_split_quali_laps(source):
 
     q1, q2, q3 = session.laps.split_qualifying_sessions()
 
+    # verify correct number of drivers per session
     assert len(q1['DriverNumber'].unique()) == 20
     assert len(q2['DriverNumber'].unique()) == 15
     assert len(q3['DriverNumber'].unique()) == 10
 
+    # verify that the last lap of q1 and q2 session is within the session time
+    # check for "early lap starts" (car crosses timing beam in pits before next
+    # session starts) being handled correctly, see #605
+    assert q1['Time'].max() < pd.Timedelta(hours=0, minutes=40)
+    assert q2['Time'].max() < pd.Timedelta(hours=1, minutes=3)
+
 
 @pytest.mark.f1telapi
 @pytest.mark.parametrize("source", ["session_status", "timing_data"])