Example 1: 

Initialize the WEIGHT and the SIGMA column of myMS.ms based on the channel widths and integration time of each visibility. dowtsp=True will create a SIGMA_SPECTRUM and WEIGHT_SPECTRUM column if they did not exist in the original myMS.ms. 

initweights(vis='myMS.ms', wtmode='nyq', dowtsp=True)


Example 2: 

Use initweights to create WEIGHT_SPECTRUM column if it does not exist and fill the WEIGHT values into WEIGHT_SPECTRUM 

initweights(vis='myMS.ms', wtmode='weight') 

 and here's a call that will remove the WEIGHT_SPECTRUM column, but keep WEIGHT

initweights(vis='myMS.ms', wrtmode='delwtsp')