floats: add ParseWithNA

floats/parse_example_test.go

@@ -0,0 +1,43 @@
+// Copyright ©2017 The gonum Authors. All rights reserved.
+// Use of this code is governed by a BSD-style
+// license that can be found in the LICENSE file
+
+package floats_test
+
+import (
+	"bufio"
+	"fmt"
+	"log"
+	"strings"
+
+	"gonum.org/v1/gonum/floats"
+	"gonum.org/v1/gonum/stat"
+)
+
+func ExampleParseWithNA() {
+	// Calculate the mean of a list of numbers
+	// ignoring missing values.
+	const data = `6
+missing
+4
+`
+
+	var vals, weights []float64
+	sc := bufio.NewScanner(strings.NewReader(data))
+	for sc.Scan() {
+		v, w, err := floats.ParseWithNA(sc.Text(), "missing")
+		if err != nil {
+			log.Fatal(err)
+		}
+		vals = append(vals, v)
+		weights = append(weights, w)
+	}
+	err := sc.Err()
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Println(stat.Mean(vals, weights))
+
+	// Output:
+	// 5
+}