Fix bug in overpass grouping

gpm/bucket/analysis.py

@@ -36,17 +36,28 @@ def get_list_overpass_time(timesteps, interval=None):
 
     This function is typically called on a regional subset of a bucket archive.
     """
+    # Check interval
     if interval is None:
         interval = np.array(60, dtype="m8[m]")
-    timesteps = sorted(timesteps)
-
+
+    # Check timesteps
+    # - Ensure numpy.datetime64
+    timesteps = np.unique(timesteps)
+    timesteps = np.sort(timesteps)
+
+    # Deal with edge cases
+    if len(timesteps) == 0:
+        raise ValueError("No timesteps available.")
+
+    if len(timesteps) == 1:
+        return [(timesteps[0], timesteps[0])]
+
     # Compute time difference
     time_diff = np.diff(timesteps)
 
     # Initialize
-    current_start_time = timesteps[0]
     list_time_periods = []
-
+    current_start_time = timesteps[0]    
     for i, dt in enumerate(time_diff):
         if i == 0:
             continue
@@ -55,11 +66,10 @@ def get_list_overpass_time(timesteps, interval=None):
             time_period = (current_start_time, end_time)
             list_time_periods.append(time_period)
             # Update
-            current_start_time = timesteps[i]
-    # Last point
-    end_time = timesteps[-1]
-    time_period = (current_start_time.astype(str), end_time.astype(str))
-    list_time_periods.append(time_period)
+            current_start_time = timesteps[i+1]
+
+    # Add the final group
+    list_time_periods.append((current_start_time, timesteps[-1]))
     return list_time_periods