gistfile1.go

package main

import (
	"encoding/csv"
	"encoding/json"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"net/url"
	"os"
	"strconv"
	"time"
)

type School struct {
	Name    string
	Address string
	Lat     float64
	Lon     float64
}

var gmaps = "http://maps.googleapis.com/maps/api/geocode/json"

func main() {
	f, err := os.Open("./data.csv")
	if err != nil {
		log.Fatalf("%s", err)
	}
	defer f.Close()

	o, err := os.Create("./output.csv")
	if err != nil {
		log.Fatalf("%s", err)
	}
	defer o.Close()

	reader := csv.NewReader(f)
	records, err := reader.ReadAll()
	if err != nil {
		log.Fatalf("error loading csv: %s", err)
	}

	var schools []School
	for _, item := range records {
		s := School{Name: item[0], Address: item[1]}

		url := gmaps + "?address=" + url.QueryEscape(s.Address) + "&sensor=false"
		// log.Printf("%s", url)
		resp, err := http.Get(url)
		if err != nil {
			log.Fatalf("gmaps error: %s", err)
		}

		defer resp.Body.Close()
		body, err := ioutil.ReadAll(resp.Body)
		if err != nil {
			log.Fatalf("resp read error: %s", err)
		}

		var jsn map[string]interface{}
		if err := json.Unmarshal(body, &jsn); err != nil {
			log.Fatalf("json unmarshal error: %s", err)
		}

		if jsn["status"].(string) != "OK" {
			break
		}

		s.Lat = jsn["results"].([]interface{})[0].(map[string]interface{})["geometry"].(map[string]interface{})["location"].(map[string]interface{})["lat"].(float64)
		s.Lon = jsn["results"].([]interface{})[0].(map[string]interface{})["geometry"].(map[string]interface{})["location"].(map[string]interface{})["lng"].(float64)

		schools = append(schools, s)

		// 0.5 sec delay in querying google
		time.Sleep(500 * time.Millisecond)

		fmt.Printf("%#v\n", s)
	}

	writer := csv.NewWriter(o)
	for _, s := range schools {
		writer.Write([]string{s.Name,
			s.Address,
			strconv.FormatFloat(s.Lat, 'f', -1, 64),
			strconv.FormatFloat(s.Lon, 'f', -1, 64),
		})
	}
	writer.Flush()

	return
}