Adding upstream version 2.1.2.

Signed-off-by: Daniel Baumann <daniel@debian.org>

examples/poly_regression/main.go

@@ -0,0 +1,39 @@
+package main
+
+//go:generate go run main.go
+
+import (
+	"os"
+
+	chart "github.com/wcharczuk/go-chart/v2"
+)
+
+func main() {
+
+	/*
+		In this example we add a new type of series, a `PolynomialRegressionSeries` that takes another series as a required argument.
+		InnerSeries only needs to implement `ValuesProvider`, so really you could chain `PolynomialRegressionSeries` together if you wanted.
+	*/
+
+	mainSeries := chart.ContinuousSeries{
+		Name:    "A test series",
+		XValues: chart.Seq{Sequence: chart.NewLinearSequence().WithStart(1.0).WithEnd(100.0)}.Values(),        //generates a []float64 from 1.0 to 100.0 in 1.0 step increments, or 100 elements.
+		YValues: chart.Seq{Sequence: chart.NewRandomSequence().WithLen(100).WithMin(0).WithMax(100)}.Values(), //generates a []float64 randomly from 0 to 100 with 100 elements.
+	}
+
+	polyRegSeries := &chart.PolynomialRegressionSeries{
+		Degree:      3,
+		InnerSeries: mainSeries,
+	}
+
+	graph := chart.Chart{
+		Series: []chart.Series{
+			mainSeries,
+			polyRegSeries,
+		},
+	}
+
+	f, _ := os.Create("output.png")
+	defer f.Close()
+	graph.Render(chart.PNG, f)
+}