This task returns statistical information about data in a MeasurementSet or Multi-MS.

The following statistics are computed: mean value, sum of values, sum of squared values, median, median absolute deviation, first and third quartiles, minimum, maximum, variance, standard deviation, and root mean square.

Statistics may be computed on any of the following axes: uvw, flag, weight, sigma, antenna1, antenna2, feed1, feed2, field_id, array_id, data_desc_id, flag_row, interval, scan, scan_number, time, weight_spectrum, amp, amplitude, phase, real, imag, and uvrange. Note that the statistics are computed on scalar values only; for example, the average amplitude is computed as a scalar average.

Additionally, statistics for any axis may be computed on subsets of the MeasurementSet partitioned by values of data description id, field id or integration number.

Optionally, the statistical information can be computed based only on a given subset of the MeasurementSet using selection parameters.

Note: If the MS consists of inhomogeneous data, it may be necessary to use selection parameters to select a homogeneous subset of the MS. For example, if the MS contains several spectral windows, each having a different number of channels, use spw='2' to run visstat on homogenous data within the MS.