Add simple command line utility

README.rst

@@ -75,6 +75,33 @@ Running this example would render the following graph:
   2.00 ┤   ╰╯    ╰╯╰╯
 ..
 
+Command line interface
+----------------------
+
+This package also brings a small utility for command line usage. Assuming
+`$GOPATH/bin` is in yout `$PATH`, simply `go get` it, and feed it data
+points via stdin:
+
+::
+
+$ go install github.com/guptarohit/asciigraph/cmd/asciigraph
+$ seq 1 72 | asciigraph -h 10 -c "plot data from stdin"
+ 72.00 ┼
+ 65.55 ┤                                                                  ╭────
+ 59.09 ┤                                                           ╭──────╯
+ 52.64 ┤                                                    ╭──────╯
+ 46.18 ┤                                             ╭──────╯
+ 39.73 ┤                                      ╭──────╯
+ 33.27 ┤                              ╭───────╯
+ 26.82 ┤                       ╭──────╯
+ 20.36 ┤                ╭──────╯
+ 13.91 ┤         ╭──────╯
+  7.45 ┤  ╭──────╯
+  1.00 ┼──╯
+          plot data from stdin
+..
+
+
 Acknowledgement
 ----------------
 This package is golang port of library `asciichart <https://github.com/kroitor/asciichart>`_ written by `@kroitor <https://github.com/kroitor>`_.

cmd/asciigraph/main.go

@@ -0,0 +1,61 @@
+package main
+
+import (
+	"bufio"
+	"flag"
+	"fmt"
+	"log"
+	"os"
+	"strconv"
+
+	"github.com/guptarohit/asciigraph"
+)
+
+var (
+	height  uint
+	width   uint
+	offset  uint = 3
+	caption string
+)
+
+func main() {
+	flag.Usage = func() {
+		fmt.Fprintf(os.Stderr, "Usage of %s:\n", os.Args[0])
+		fmt.Fprintf(os.Stderr, "  %s [options]\n", os.Args[0])
+		fmt.Fprintf(os.Stderr, "Options:\n")
+		flag.PrintDefaults()
+		fmt.Fprintf(os.Stderr, "%s expects data points from stdin. Invalid values are logged to stderr.", os.Args[0])
+	}
+	flag.UintVar(&height, "h", height, "`height` in text rows, 0 for auto-scaling")
+	flag.UintVar(&width, "w", width, "`width` in columns, 0 for auto-scaling")
+	flag.UintVar(&offset, "o", offset, "`offset` in columns, for the label")
+	flag.StringVar(&caption, "c", caption, "`caption` for the graph")
+	flag.Parse()
+
+	data := make([]float64, 0, 64)
+
+	s := bufio.NewScanner(os.Stdin)
+	s.Split(bufio.ScanWords)
+	for s.Scan() {
+		p, err := strconv.ParseFloat(s.Text(), 64)
+		if err != nil {
+			continue
+		}
+		data = append(data, p)
+	}
+	if err := s.Err(); err != nil {
+		log.Fatal(err)
+	}
+
+	if len(data) == 0 {
+		log.Fatal("no data")
+	}
+
+	plot := asciigraph.Plot(data,
+		asciigraph.Height(int(height)),
+		asciigraph.Width(int(width)),
+		asciigraph.Offset(int(offset)),
+		asciigraph.Caption(caption))
+
+	fmt.Println(plot)
+}