1.2.1.0 ms.putdata

1.2.1 Write new values into the measurement set
Description

This function allows you to write values from casapy variables back into the measurement set table. The main difference between this and directly accessing the table using the table tool is that this function writes data to the selected measurement set.

Unlike the getdata function you can only put items that correspond to actual table columns. You cannot change the data shape either so that the number of correlations, channels and rows (or intereferometers/time slots) must match the values in the selected measurement set. If the values were obtained using the getdata function with ifraxis argument set to True, then any default values added to fill in missing intereferometer/timeslots pairs will be ignored when writing the modified values back using this function.

The measurement set has to be opened for read/write access to be able to use this function.

You need to call selectinit before calling this function. If you haven’t then selectinit will be called for you with default arguments.

Items prefixed with either; corrected, model, residual or obs_residual and the imaging_weight item are not available unless your measurement set has been processed either with the imager or calibrator tools.


Inputs
items	Record with items and their new values
	allowed:	any
	Default:	record

      ms.open("3C273XC1.MS", nomodify=False)
      ms.selectinit(datadescid=0)
      rec = ms.getdata(["weight","data"])
      rec[’weight’][:,:] = 1
      import Numeric
      meanrec = Numeric.average(rec[’data’],axis=None)
      print "Mean data value = ", meanrec
      rec[’data’][:,:,:] -= meanrec
      ms.putdata(rec)

This example selects all the data from the measurement set where the value in the DATA_DESC_ID column is zero. This corresponds to a particular spectral window and polarization setup. Note that the measurement set was opened for writing as well as reading. The third line reads all the weights and the data into the casapy variable rec. The weights are set to one. The more obscure syntax is used as typing rec[’weight’] = 1 will not preserve the shape of the weight array. The data then has its mean subtracted from it. The average function is defined in Numeric module. Finally the data is written back into the measurement set table. (NOTE: normally one should not modify the raw data column. Such adjustments are more appropriate for the corrected_data column, if it exists.)

ms.putdata - Function