[ Basic Info | User Guide ]
Basic Information on uvflag
Purpose: Flags or unflags uv data
Categories: calibration, uv analysis
UVFLAG is used to change flags corresponding to visibility data.
Using the keywords select, line and edge one selects a portion of a
uv-data file. For all selected correlations the flags are then set to
the value specified with the keyword flagval. If flagval equals
'flag', the uv data are flagged as bad; for flagval equal to 'unflag',
the uv data are flagged as good.
The user can control the amount of output produced using the options
keyword. Only records that fulfill all selection criteria as
specified by select, line and edge are shown and counted, not the
Because the physical writing of the flags is done using a buffering
approach, the flags are only actually changed in the datafile if
one lets uvflag finish normally. I.e., if the 'q' option is used to
stop printing, the flags may or may not have been changed.
UVFLAG can also be used to inspect the uv-data. If option 'noapply'
is used, everything works as it would do normally, except that the
flags are not actually changed in the datafile. This is particularly
useful in combination with option 'full'.
Standard keyword vis. See the help on vis for more information.
Multiple input datasets are allowed.
Standard keyword select. See the help on select for more information.
Standard keyword line. See the help on line for more information.
Uvflag supports only types 'channel and wide'. If line is
unspecified, both the 'channel data' and the 'wideband data'
(if present) will be flagged. Also, since averaging of data
is an undefined operation when setting flags, width is
forced to be equal to 1.
This keyword allows uvflag to work on the edges of spectral
windows. Three numbers may be given, n, m and c. Flags will
be changed only for the first n and last m channels of each
spectral window and for the central c channels.
If one value is given, the number of selected channels at
the start and end of the window is assumed to be equal.
If two values are given the first gives the number of
selected channels at the start, the second the number at
the end. In this case either one may also be 0.
The third value gives the number of channels to delete from
the center of the band. The default is 0. The center of a
window is defined as 'startchannel+nchannels/2'.
A negative value is interpreted as meaning that the beginning,
ending, or middle 1/8th of the band must be deleted.
Use of the edge keyword forces the step parameter of the
line keyword to be equal to 1.
Edge cannot be combined with linetype 'wide'. If edge is
used, the linetype defaults to channel,0,1,1,1, i.e. all
This also works for multiple input visibility files, even
if these have different correlator modes.
Either 'flag' or 'unflag', which tells whether the flags for
the correlations selected by 'select', 'line' and 'edge'
have to be set or unset. May be abbreviated to 'f' or 'u'.
Exactly one of the options 'flag' or 'unflag' must be
One or more of
'none', 'brief', 'indicative', 'full', 'noquery',
These options can be abbreviated to uniqueness. The default
is 'brief,hms', except when a logfile is given (see keyword
log), then it becomes 'indicative,hms'.
'noapply' will go through the whole process without
actually changing the flags. Useful for checking what will
happen or for inspecting the flags.
No history comments are written.
'none', 'brief', 'indicative' and 'full' control the
amount of information returned to the user.
- 'brief' gives an overview when UVFLAG finishes.
- 'indicative' lists the number of good, bad and changed
flags for each selected uv-record.
- 'full' lists the data, the old flag and the new flag for
each channel separately and also an overview of each record.
- If more than 1 verbosity level is given, the lowest is taken.
- Option 'noquery' will turn off the feature that printing
is halted every 22 lines.
For verbosity levels 'indicative' and 'full' the format
of the time that is written is determined by 'hms' (hours,
minutes and seconds) or 'decimal' (decimal parts of a day).
Name of a file where reported information is written.
If empty this implies the terminal screen, else the
named file. Giving a filename also sets option 'indicative'.
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