Resolve "Get time windows for labels"

Closes #20 (closed)

skais/ais/ais_trajectory.py

@@ -215,5 +215,11 @@ class AISTrajectory(AISPoints):
         else:
             return AISTrajectory(new_df, mmsi=self.mmsi)
 
-    def get_time_per_label_shift(self):
-        pass
\ No newline at end of file
+    def get_time_per_label_shift(self, label_column='label'):
+        current_label = -1
+        result = []
+        for index, row in self.df.iterrows():
+            if current_label != row[label_column]:
+                current_label = row[label_column]
+                result.append((row['ts_sec'], current_label))
+        return result
\ No newline at end of file