- add plot compatibility with go-chart pkg

README.md

@@ -191,6 +191,32 @@ median, _ := stats.Median(sf.Values)
 std := stat.StdDev(sf.Values, nil)
 ```
 
+## Plotting (only Windows, macOS and Linux)
+
+```go
+import (
+	"github.com/rocketlaunchr/dataframe-go/plot"
+	c "github.com/rocketlaunchr/dataframe-go/plot/wcharczuk/go-chart"
+)
+
+sales := dataframe.NewSeriesFloat64("sales", nil, 50.3, nil, 23.4, 56.2, 89, 32, 84.2, 72, 89)
+cs, _ := c.S(ctx, sales, nil)
+
+graph := chart.Chart{Series: []chart.Series{cs}}
+
+plt, _ := plot.Open("Monthly sales", 450, 300)
+graph.Render(chart.SVG, plt)
+plt.Display(plot.SVG)
+<-plt.Closed
+
+```
+
+Output:
+
+<p align="center">
+<img src="https://github.com/rocketlaunchr/dataframe-go/raw/master/plot.png" alt="plot" />
+</p>
+
 ## Importing Data
 
 The `imports` sub-package has support for importing csv, jsonl and directly from a SQL database. The `DictateDataType` option can be set to specify the true underlying data type. Alternatively, `InferDataTypes` option can be set.

helpers.go

@@ -26,6 +26,21 @@ func B(b bool) int {
 	return 0
 }
 
+// IsValidFloat64 returns true if f is neither Nan nor ±Inf.
+// Otherwise it returns false.
+func IsValidFloat64(f float64) bool {
+
+	if isNaN(f) {
+		return false
+	}
+
+	if isInf(f, 0) {
+		return false
+	}
+
+	return true
+}
+
 // BoolValueFormatter is used by SetValueToStringFormatter
 // to display an int as a bool. If the encountered value
 // is not a 0 or 1, it will panic.

plot/plot.go

@@ -1,3 +1,5 @@
+// Copyright 2018-20 PJ Engineering and Business Solutions Pty. Ltd. All rights reserved.
+
 package plot
 
 import (

plot/wcharczuk/go-chart/chart.go

@@ -0,0 +1,107 @@
+// Copyright 2018-20 PJ Engineering and Business Solutions Pty. Ltd. All rights reserved.
+
+package chart
+
+import (
+	"context"
+	"time"
+
+	"github.com/wcharczuk/go-chart"
+
+	dataframe "github.com/rocketlaunchr/dataframe-go"
+)
+
+// S converts a SeriesFloat64 to a chart.Series for usage with the "github.com/wcharczuk/go-chart" package.
+// Currently x can be nil, a SeriesFloat64 or a SeriesTime. nil values in the x and y Series are ignored.
+func S(ctx context.Context, y *dataframe.SeriesFloat64, x interface{}, r ...dataframe.Range) (chart.Series, error) {
+
+	var out chart.Series
+
+	if len(r) == 0 {
+		r = append(r, dataframe.Range{})
+	}
+
+	yNRows := y.NRows(dataframe.DontLock)
+
+	start, end, err := r[0].Limits(yNRows)
+	if err != nil {
+		return nil, err
+	}
+
+	switch xx := x.(type) {
+	case nil:
+		cs := chart.ContinuousSeries{Name: y.Name(dataframe.DontLock)}
+
+		xVals := []float64{}
+		yVals := []float64{}
+
+		// Remove nil values
+		for i, j := 0, start; j < end+1; i, j = i+1, j+1 {
+			yval := y.Values[j]
+
+			if dataframe.IsValidFloat64(yval) {
+				yVals = append(yVals, yval)
+				xVals = append(xVals, float64(i))
+			}
+		}
+
+		cs.XValues = xVals
+		cs.YValues = yVals
+
+		out = cs
+	case *dataframe.SeriesFloat64:
+
+		cs := chart.ContinuousSeries{Name: y.Name(dataframe.DontLock)}
+
+		xVals := []float64{}
+		yVals := []float64{}
+
+		// Remove nil values
+		for i, j := 0, start; j < end+1; i, j = i+1, j+1 {
+			yval := y.Values[j]
+			xval := xx.Values[j]
+
+			if dataframe.IsValidFloat64(yval) {
+				// Check x val is valid
+				if dataframe.IsValidFloat64(xval) {
+					yVals = append(yVals, yval)
+					xVals = append(xVals, xval)
+				}
+			}
+		}
+
+		cs.XValues = xVals
+		cs.YValues = yVals
+
+		out = cs
+	case *dataframe.SeriesTime:
+
+		cs := chart.TimeSeries{Name: y.Name(dataframe.DontLock)}
+
+		xVals := []time.Time{}
+		yVals := []float64{}
+
+		// Remove nil values
+		for i, j := 0, start; j < end+1; i, j = i+1, j+1 {
+			yval := y.Values[j]
+			xval := xx.Values[j]
+
+			if dataframe.IsValidFloat64(yval) {
+				// Check x val is valid
+				if xval != nil {
+					yVals = append(yVals, yval)
+					xVals = append(xVals, *xval)
+				}
+			}
+		}
+
+		cs.XValues = xVals
+		cs.YValues = yVals
+
+		out = cs
+	default:
+		panic("unrecognized x")
+	}
+
+	return out, nil
+}