Getting Started | Documentation | Glish | Learn More | Programming | Contact Us |
Version 1.9 Build 1488 |
|
Package | general | |
Module | ms | |
Tool | ms |
datadescid | in | Data description id | |
Allowed: | integer | ||
Default: | 0 | ||
reset | in | Reset to unselected state | |
Allowed: | Boolean | ||
Default: | F |
The DATA_DESC_ID
column in the measurement set contains a
value that maps to a particular row in the POLARIZATION
and
SPECTRAL_WINDOW
subtables. Hence all rows with the same
value in the DATA_DESC_ID
column must have the same data
shape. To select all the data where the DATA_DESC_ID
value
is N you call this function with the datadescid argument set to
N + 1. The examples below make this a bit clearer.
It is possible to have a measurement set with differing values in
the DATA_DESC_ID
column but where all the data is a fixed
shape. For example this will occur if the reference frequency
changes but the number of spectral channels is fixed. In cases
like this all the data can be selected, using this function with
an argument of zero. If the data shape does change and you call
this function with an datadescid set to zero it is equivalent to
calling this function with datadescid set to one. When this
happens the return value will be F. In all other cases it will be
T.
To return to the completely unselected measurement set, set the reset argument to True. This will allow you to acces the full range of rows in the measurement set, rather than just the selected measurement set.
The datadescid must always be a non-negative integer.
include 'ms.g' myms := ms("3C273XC1.ms"); myms.selectinit(datadescid=1); print myms.range("uvdist"); myms.selectinit(reset=T); print myms.range("uvdist");In this example displays the range of uv distances for the data in the specified measurement set. The first print statement will only use data where the
DATA_DESC_ID
column is 0. This will
correspond to a specific spectral window and polarization
setup. The second print statement will print the range of uv
distances for all the data in measurement set.