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using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace Routeguide
{
/// <summary>
/// Utility methods for the route guide example.
/// </summary>
public static class RouteGuideUtil
{
public const string DefaultFeaturesFile = "route_guide_db.json";
private const double CoordFactor = 1e7;
/// <summary>
/// Indicates whether the given feature exists (i.e. has a valid name).
/// </summary>
public static bool Exists(this Feature feature)
{
return feature != null && (feature.Name.Length != 0);
}
public static double GetLatitude(this Point point)
{
return point.Latitude / CoordFactor;
}
public static double GetLongitude(this Point point)
{
return point.Longitude / CoordFactor;
}
/// <summary>
/// Calculate the distance between two points using the "haversine" formula.
/// This code was taken from http://www.movable-type.co.uk/scripts/latlong.html.
/// </summary>
/// <param name="start">the starting point</param>
/// <param name="end">the end point</param>
/// <returns>the distance between the points in meters</returns>
public static double GetDistance(this Point start, Point end)
{
double lat1 = start.GetLatitude();
double lat2 = end.GetLatitude();
double lon1 = start.GetLongitude();
double lon2 = end.GetLongitude();
int r = 6371000; // metres
double phi1 = ToRadians(lat1);
double phi2 = ToRadians(lat2);
double deltaPhi = ToRadians(lat2 - lat1);
double deltaLambda = ToRadians(lon2 - lon1);
double a = Math.Sin(deltaPhi / 2) * Math.Sin(deltaPhi / 2) + Math.Cos(phi1) * Math.Cos(phi2) * Math.Sin(deltaLambda / 2) * Math.Sin(deltaLambda / 2);
double c = 2 * Math.Atan2(Math.Sqrt(a), Math.Sqrt(1 - a));
return r * c;
}
/// <summary>
/// Returns <c>true</c> if rectangular area contains given point.
/// </summary>
public static bool Contains(this Rectangle rectangle, Point point)
{
int left = Math.Min(rectangle.Lo.Longitude, rectangle.Hi.Longitude);
int right = Math.Max(rectangle.Lo.Longitude, rectangle.Hi.Longitude);
int top = Math.Max(rectangle.Lo.Latitude, rectangle.Hi.Latitude);
int bottom = Math.Min(rectangle.Lo.Latitude, rectangle.Hi.Latitude);
return (point.Longitude >= left && point.Longitude <= right && point.Latitude >= bottom && point.Latitude <= top);
}
private static double ToRadians(double val)
{
return (Math.PI / 180) * val;
}
/// <summary>
/// Parses features from a JSON file.
/// </summary>
public static List<Feature> ParseFeatures(string filename)
{
var features = new List<Feature>();
var jsonFeatures = JsonConvert.DeserializeObject<List<JsonFeature>>(File.ReadAllText(filename));
foreach(var jsonFeature in jsonFeatures)
{
features.Add(new Feature
{
Name = jsonFeature.name,
Location = new Point { Longitude = jsonFeature.location.longitude, Latitude = jsonFeature.location.latitude}
});
}
return features;
}
private class JsonFeature
{
public string name;
public JsonLocation location;
}
private class JsonLocation
{
public int longitude;
public int latitude;
}
}
}
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