import Graph def NewElem(Item): if isinstance(Item, Graph.TStdFunc) and isinstance(Graph.Selected, Graph.TPointSeries): if "R²" in Item.LegendText: # Silly way to detect that a function is a newly created trendline ResidualSeries = Graph.TPointSeries() ResidualSeries.LegendText = "Residual plot" ResidualSeries.LineSize = 0 ResidualSeries.Size = 4 ResidualSeries.Style = 2 for (x,y) in Graph.Selected.Points: ResidualSeries.Points.append((x, y - Item.Eval(x)[1])) Graph.FunctionList.append(ResidualSeries) Graph.Redraw() Graph.OnNewElem.append(NewElem)