title: Straight line calculation/forecast
body: <p>I have 4 columns of data: store name, ship date start, ship date end, #of boxes.  I would like in Spotfire create new columns or rows for the time period listed by month and have the monthly #of boxes be calculated and populated.  For example Jan 2019 to Dec 2019 for 1200 boxes would mean 100 boxes per month.</p>