Use taql + mscal instead of virtual columns

This fixes #174. Using virtual columns is not advised, since it changes the measurement set. The taql call with the use of mscal calls exactly the same functions but without changing the MS.
lofar-astron · Oct 16, 2018 · 6629385 · 6629385
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commit 6629385
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Showing 2 changed files with 8 additions and 26 deletions.
diff --git a/scripts/InitSubtract_deep_sort_and_compute.py b/scripts/InitSubtract_deep_sort_and_compute.py
@@ -58,23 +58,14 @@ def get_image_sizes(self, cellsize_highres_deg=None, cellsize_lowres_deg=None,
             self.cellsize_lowres_deg = cellsize_lowres_deg
         if not hasattr(self, 'mean_el_rad'):
             for MS_id in xrange(self.numMS):
-                # Add (virtual) elevation column to MS
-                try:
-                    pt.addDerivedMSCal(self.files[MS_id])
-                except RuntimeError:
-                    # RuntimeError indicates column already exists
-                    pass
-
                 # calculate mean elevation
                 tab = pt.table(self.files[MS_id], ack=False)
+                el_values = pt.taql("SELECT mscal.azel1()[1] AS el from "
+                                    + self.files[MS_id] + " limit ::10000").getcol("el")
                 if MS_id == 0:
-                    global_el_values = tab.getcol('AZEL1', rowincr=10000)[:, 1]
+                    global_el_values = el_values
                 else:
-                    global_el_values = np.hstack( (global_el_values, tab.getcol('AZEL1', rowincr=10000)[:, 1]) )
-                tab.close()
-
-                # Remove (virtual) elevation column from MS
-                pt.removeDerivedMSCal(self.files[MS_id])
+                    global_el_values = np.hstack( (global_el_values, el_values ) )
             self.mean_el_rad = np.mean(global_el_values)
 
         # Calculate mean FOV

diff --git a/scripts/InitSubtract_sort_and_compute.py b/scripts/InitSubtract_sort_and_compute.py
@@ -56,23 +56,14 @@ def get_image_sizes(self, cellsize_highres_deg=None, cellsize_lowres_deg=None,
             self.cellsize_lowres_deg = cellsize_lowres_deg
         if not hasattr(self, 'mean_el_rad'):
             for MS_id in xrange(self.numMS):
-                # Add (virtual) elevation column to MS
-                try:
-                    pt.addDerivedMSCal(self.files[MS_id])
-                except RuntimeError:
-                    # RuntimeError indicates column already exists
-                    pass
-
                 # calculate mean elevation
                 tab = pt.table(self.files[MS_id], ack=False)
+                el_values = pt.taql("SELECT mscal.azel1()[1] AS el from "
+                                    + self.files[MS_id] + " limit ::10000").getcol("el")
                 if MS_id == 0:
-                    global_el_values = tab.getcol('AZEL1', rowincr=10000)[:, 1]
+                    global_el_values = el_values
                 else:
-                    global_el_values = np.hstack( (global_el_values, tab.getcol('AZEL1', rowincr=10000)[:, 1]) )
-                tab.close()
-
-                # Remove (virtual) elevation column from MS
-                pt.removeDerivedMSCal(self.files[MS_id])
+                    global_el_values = np.hstack( (global_el_values, el_values ) )
             self.mean_el_rad = np.mean(global_el_values)
 
         # Calculate mean FOV