L2SS-674: Fix statistics_writer for multiple subbands in XST

tangostationcontrol/tangostationcontrol/statistics_writer/hdf5_writer.py

@@ -253,7 +253,10 @@ class xst_hdf5_writer(hdf5_writer):
 
     def write_values_matrix(self, current_group):
         # requires a function call to transform the xst_blocks in to the right structure
-        current_group.create_dataset(name="values", data=self.current_matrix.xst_values([self.subband_index])[0].astype(numpy.cfloat), compression="gzip")
+        #
+        # since we have a dedicated writer per subband_index, they all end up in slot 0
+        # in their writer, so we only need to store the first set of xst_values.
+        current_group.create_dataset(name="values", data=self.current_matrix.xst_values([0])[0].astype(numpy.cfloat), compression="gzip")
 
 
 class parallel_xst_hdf5_writer:
@@ -265,15 +268,12 @@ class parallel_xst_hdf5_writer:
 
         # function to create a new writer, to avoid having to store
         # all the init parameters just for this purpose.
-        #
         def new_writer(subband):
-            # Since we use a dedicated writer per subband, the data will end
-            # up at subband_index == 0 in each of them.
             return xst_hdf5_writer(
                        new_file_time_interval,
                        file_location,
                        decimation_factor,
-                       0)
+                       subband)
 
         self.new_writer = new_writer