2.1.1.0 autoflag.setsprej

autoflag.setsprej - Function

2.1.1 Sets up the spectral rejection flagging method
Description

The sprej method works by fitting a user-specified segment of the spectrum (presumably, the continuum) by a polynomial. It then flags entire rows based on the chi-square statistic of the fit, in a manner similar to timemed. Please refer to setimemed for detailed math, substituting χ_bt² for M_bt. The value that is actually fitted is specified via the expr parameter (see the general ?? description for details).

The segement to be fitted can be specified as a range of channel indices (1-based) or frequencies. Frequencies may be given as string measures ("1.4GHz") or float values (units of MHz assumed). A vector of two values [C1,C2] specifies the segment from C1 to C2, inclusive. Several disjoint segments may be specified with a 2N vector or a (2,N) matrix.

For a measurement set containing multiple spectral windows, you can set the region argument to a record of records, with each sub-record containing spwid and fq and/or chan fields, specifying the segments of a specific spectral window. See examples below.

Arguments


Inputs
ndeg	Number of degrees for polynomial
	allowed:	int
	Default:	2
rowthr	Flagging threshold, in MADs of χ²
	allowed:	double
	Default:	5.0
rowhw	Half-window for the sliding median
	allowed:	int
	Default:	6
norow	Disable row flagging
	allowed:	bool
	Default:	false
spwid	Spectral window number (0-based), or -1 for all windows
	allowed:	int
	Default:	-1
chan	Range of channels (0-based). Either “fq” or “chan” must be specified, 2N or (2,N).
	allowed:	intArray
	Default:	-1 -1
region	A compound spectral segment specification (see example)
	allowed:	any
	Default:	record
column	Which column to base flagging on
	allowed:	string
	Default:	MODEL CORR” DATA
expr	Expression to use
	allowed:	string
	Default:	ABS I
fignore	Ignore existing flags
	allowed:	bool
	Default:	false

Returns
bool

Example

- af:=autoflag(’3C273XC1.MS’)
- af.setdata()
# use segments 807-807.5 and 809-809.5 MHz for fitting
- af.setsprej(fq=[807,807.5,809,809.5))
...
# use channels 10-20 and 30-40
- af.setsprej(chan=[[10,20],[30,40]])
...
# use different segements in different spectral windows
- region := [=]
- region[1] := [ spwid=1,fq="1.4GHz 1.401GHz" ]
- region[2] := [ spwid=2,chan=[10,20] ]
- region[3] := [ spwid=4,chan=[50,60] ]
- af.setsprej(region=region)

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