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calibrater.setdata - Function

	Package	synthesis
	Module	calibrater
	Tool	calibrater

Set the data selection for subsequent processing

Synopsis
setdata(mode, nchan, start, step, mstart, mstep, uvrange, msselect)

Arguments

mode	in	Type of data selection: channel or velocity
		Allowed:	String from 'none'|'channel'|'velocity'
		Default:	'none'
nchan	in	Number of channels to select (mode='channel')
		Allowed:	Int
		Default:	1
start	in	Start channel (1-relative) (mode='channel'
		Allowed:	Int
		Default:	1
step	in	Step in channel number (mode='channel')
		Allowed:	Int
		Default:	1
mstart	in	Start velocity (e.g. '20Km/s')
		Allowed:	Quantity
		Default:	'0km/s'
mstep	in	Step in velocity (e.g. '100m/s'
		Allowed:	Quantity
		Default:	'0km/s'
uvrange	in	UV range (in klambda) (e.g. [0, 50]). Default is no restriction.
		Allowed:	Vector of Doubles
		Default:	0
msselect	in	TAQL selection string. Default is no selection.
		Allowed:	String
		Default:	' '

Returns
Bool

Description

This function selects which data will be treated by subsequent execution of the solve and correct functions. Note that data selection is not cumulative; any selection made in a previous call is replaced by the selection from the current call.

The arguments are used as follows:

mode

indicates how you select the desired channels. A value of 'none' means select all data (make no channel selection); all channel- or velocity-dependent arguments are ignored in this case. A value of 'channel' indicates that you select by channel number. A value of 'velocity' indicates that you select by radio velocity and a value 'opticalvelocity' indicates that you select by optical velocity.

nchan

is the number of selected channels for mode='channel'. It defaults to 1; to select all channels, set to 0.

start

is active only when mode='channel' and specifies the first channel to be selected. It defaults to 1.

step

is active only when mode='channel' and specifies the increment between selected input channels. It defaults to 1.

The channels are centered on velocities: start, start+step, start+2*step, etc.

mstart

is active only when mode='velocity' or mode='optical velocity'. It specifies the start velocity to select as a quantity string. The default is 0.

mstep

is active only when mode='velocity' or mode='optical velocity'. It specifies the increment between selected channels as a quantity string. The default is 0 which is not very useful...

The channels are centered on velocities: mstart, mstart+mstep, mstart+2*mstep, etc.

msselect

is used to specify a subselection of data according to field, spectral window, time, etc., and should be specified as a valid TaQL expression.

Example

c:=calibrater('3C273XC1.MS');

Select according to channel:

c.setdata(mode='channel',nchan=512,start=1,step=1,msselect='FIELD_ID==1')

Select according to velocity:

c.setdata(mode='velocity', nchan=64, mstart='20km/s', mstep='-100m/s');

Reset selection to the entire dataset

c.setdata()