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autoflag.setuvbin - Function

	Package	synthesis
	Module	autoflag
	Tool	autoflag

Sets up the UV Binner flagging method

Synopsis
setuvbin(thr, minpop, nbins, plotchan, econoplot, column, expr, fignore)

Description

The uvbin method works by binning the data on a value vs. UV-distance plane (value is determined by the expr parameter - see the general autoflag module description for a description of this mechanism.) Data in underpopulated bins is then flagged.

The cut-off point for flagging may be expressed in one of two ways:

• If the maxpop parameter is specified (e.g. maxpop=4), all bins with less than maxpop points are flagged.

• If the thr parameter is specified, a probability cut-off is selected. This is done as follows. The cumulative probability p(N), defined as the probability for a given point to reside in a bin of a population $\le$N, is first computed. All bins of population N, where p(N) <thr, are then flagged.

  In simpler terms, using thr=0.01 will flag up to 1% of your data points, beginning with the least populous bins. I.e., first the single-point bins are flagged, then the 2-point bins, and so on, up to the N - 1-point bins, where N is such that flagging the N-point bins would exceed 1% of all data points.

• When both maxpop and thr are specified, uvbin will use the higher of the two resulting cut-offs.

Uvbin can be asked to produce a value vs. UV-distance plot, and a plot of p(N). These plots are attached to the flagging report. Uuse of the econoplot mode is recommended when dealing with medium-to-large data sets, for significant reduction in plot file size and printing time.

Arguments

thr		Population cut-off, as p(N) value.
		Allowed:	Float, 0 for none
		Default:	0
minpop		Population cut-off, as minimum bin count. Either thr or maxpop must be specified, or both.
		Allowed:	Int, 0 for none
		Default:	0
nbins		Number of bins (one number for both axes, or separate for UV, value)
		Allowed:	Int or 2 Ints
		Default:	50
plotchan		Channel number (1-based) to plot, T for middle channel, or F for no plot
		Allowed:	Int or Bool
		Default:	F
econoplot		Produce an economical plot (crowded bins are not resolved)
		Allowed:	Bool
		Default:	F
column		Which column to base flagging on
		Allowed:	"DATA", "MODEL" or "CORR"
		Default:	"DATA"
expr		Expression to use
		Allowed:	see text
		Default:	"ABS I"
fignore		Ignore existing flags
		Allowed:	Bool
		Default:	F

Example

- af:=autoflag('3C273XC1.MS')
- af.setdata()
- af.setuvbin(nbins=[50,100],expr="- ABS RR LL",plotchan=40,econoplot=T)