Fix bug in NetCDF creation masking all values

aosstower/level_b1/nc.py

@@ -37,7 +37,8 @@ def _get_data(input_files):
 
 def get_data(input_files):
     frame = pd.DataFrame(_get_data(input_files))
-    frame = frame.set_index('stamp').mask(frame == -99999.).fillna(value=np.nan)
+    frame = frame.set_index('stamp')
+    frame = frame.mask(frame == -99999.).fillna(value=np.nan)
     return frame