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ms.selectpolarization - Function

	Package	general
	Module	ms
	Tool	ms

Select and convert of polarizations

Synopsis
selectpolarization(wantedpol)

Arguments

wantedpol		The polarizations wanted
		Allowed:	Vector of strings
		Default:	no default

Returns
Boolean

Description
This function allows you to select a subset of the polarizations in the current measurement set. This function can also setup conversion to different polarization representations.

You specify the polarizations using a string vector. Allowable strings are include I, Q, U, V, RR, RL, LR, LL, XX, YY, XY, YX. These string must be specified in upper case. If the polarizations match those present in the measurement set they will be selected directly, otherwise all polarizations are read and then a conversion step is done. If the conversion cannot be done then an error will be produced when you try to access the data.

This function return T if the selection was successful, and F if not.

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

Example

      include 'ms.g'
      myms:=ms("3C273XC1.ms");
      myms.selectinit(datadescid=1);
      myms.selectpolarization("I V");
      rec := myms.getdata("data");

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. It then selects the I and V polarizations and when the getdata function is called the conversion from RR, LL, LR, RL polarizations to I and V occurs.