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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()





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Next: calibrater.setapply - Function Up: calibrater - Tool Previous: calibrater - Constructor   Contents   Index
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2006-10-15