to draw the boundary line between True and False regions on a boolean 2d array. Without levels=[.5], one gets the default 8 levels which go at 0, 0.15, 0.3, 0.45, 0.6, 0.75, 0.9, 1.05 resulting in all ...

Churn is an early-life problem: customers in their first 12 months churn at 47.4%, falling to 9.5% after four years. New month-to-month customers (12 months or less) are the core problem: 1,994 ...