|
1 |
| -using System; |
2 |
| -using System.Collections.Generic; |
3 |
| -using System.Linq; |
4 | 1 | using System.Text;
|
5 |
| -using System.Threading.Tasks; |
6 | 2 |
|
7 |
| -namespace Algorithms.Other |
| 3 | +namespace Algorithms.Other; |
| 4 | + |
| 5 | +public static class Geohash |
8 | 6 | {
|
9 |
| - public static class Geohash |
| 7 | + private const string Base32Characters = "0123456789bcdefghjkmnpqrstuvwxyz"; // Convert latitude and longitude coordinates into a concise string |
| 8 | + private const int GeohashLength = 12; // ± 1.86 cm |
| 9 | + |
| 10 | + /// <summary> |
| 11 | + /// Encodes the provided latitude and longitude coordinates into a Geohash string. |
| 12 | + /// Geohashing is a method to encode geographic coordinates (latitude, longitude). |
| 13 | + /// into a short string of letters and digits. Each character in the resulting Geohash . |
| 14 | + /// string adds more precision to the location. The longer the Geohash, the smaller the area. |
| 15 | + /// </summary> |
| 16 | + /// <param name="latitude">The latitude of the location to encode. It must be a value between -90 and 90.</param> |
| 17 | + /// <param name="longitude">The longitude of the location to encode. It must be a value between -180 and 180.</param> |
| 18 | + /// <returns> |
| 19 | + /// A Geohash string of length 12 representing the location with high precision. |
| 20 | + /// A longer Geohash provides higher precision in terms of geographic area. |
| 21 | + /// and a 12-character Geohash can be accurate down to around 1.86 cm. |
| 22 | + /// </returns> |
| 23 | + public static string Encode(double latitude, double longitude) |
10 | 24 | {
|
11 |
| - private const string Base32Characters = "0123456789bcdefghjkmnpqrstuvwxyz"; // Convert latitude and longitude coordinates into a concise string |
12 |
| - private const int GeohashLength = 12; // ± 1.86 cm |
| 25 | + double[] latitudeRange = new[] { -90.0, 90.0 }; |
| 26 | + double[] longitudeRange = new[] { -180.0, 180.0 }; |
| 27 | + bool isEncodingLongitude = true; |
| 28 | + int currentBit = 0; |
| 29 | + int base32Index = 0; |
| 30 | + StringBuilder geohashResult = new StringBuilder(); |
13 | 31 |
|
14 |
| - /// <summary> |
15 |
| - /// Encodes the provided latitude and longitude coordinates into a Geohash string. |
16 |
| - /// Geohashing is a method to encode geographic coordinates (latitude, longitude). |
17 |
| - /// into a short string of letters and digits. Each character in the resulting Geohash . |
18 |
| - /// string adds more precision to the location. The longer the Geohash, the smaller the area. |
19 |
| - /// </summary> |
20 |
| - /// <param name="latitude">The latitude of the location to encode. It must be a value between -90 and 90.</param> |
21 |
| - /// <param name="longitude">The longitude of the location to encode. It must be a value between -180 and 180.</param> |
22 |
| - /// <returns> |
23 |
| - /// A Geohash string of length 12 representing the location with high precision. |
24 |
| - /// A longer Geohash provides higher precision in terms of geographic area. |
25 |
| - /// and a 12-character Geohash can be accurate down to around 1.86 cm. |
26 |
| - /// </returns> |
27 |
| - public static string Encode(double latitude, double longitude) |
| 32 | + while (geohashResult.Length < GeohashLength) |
28 | 33 | {
|
29 |
| - double[] latitudeRange = new[] { -90.0, 90.0 }; |
30 |
| - double[] longitudeRange = new[] { -180.0, 180.0 }; |
31 |
| - bool isEncodingLongitude = true; |
32 |
| - int currentBit = 0; |
33 |
| - int base32Index = 0; |
34 |
| - StringBuilder geohashResult = new StringBuilder(); |
| 34 | + double midpoint; |
35 | 35 |
|
36 |
| - while (geohashResult.Length < GeohashLength) |
| 36 | + if (isEncodingLongitude) |
37 | 37 | {
|
38 |
| - double midpoint; |
39 |
| - |
40 |
| - if (isEncodingLongitude) |
| 38 | + midpoint = (longitudeRange[0] + longitudeRange[1]) / 2; |
| 39 | + if (longitude > midpoint) |
41 | 40 | {
|
42 |
| - midpoint = (longitudeRange[0] + longitudeRange[1]) / 2; |
43 |
| - if (longitude > midpoint) |
44 |
| - { |
45 |
| - base32Index |= 1 << (4 - currentBit); |
46 |
| - longitudeRange[0] = midpoint; |
47 |
| - } |
48 |
| - else |
49 |
| - { |
50 |
| - longitudeRange[1] = midpoint; |
51 |
| - } |
| 41 | + base32Index |= 1 << (4 - currentBit); |
| 42 | + longitudeRange[0] = midpoint; |
52 | 43 | }
|
53 | 44 | else
|
54 | 45 | {
|
55 |
| - midpoint = (latitudeRange[0] + latitudeRange[1]) / 2; |
56 |
| - if (latitude > midpoint) |
57 |
| - { |
58 |
| - base32Index |= 1 << (4 - currentBit); |
59 |
| - latitudeRange[0] = midpoint; |
60 |
| - } |
61 |
| - else |
62 |
| - { |
63 |
| - latitudeRange[1] = midpoint; |
64 |
| - } |
| 46 | + longitudeRange[1] = midpoint; |
65 | 47 | }
|
66 |
| - |
67 |
| - isEncodingLongitude = !isEncodingLongitude; |
68 |
| - |
69 |
| - if (currentBit < 4) |
| 48 | + } |
| 49 | + else |
| 50 | + { |
| 51 | + midpoint = (latitudeRange[0] + latitudeRange[1]) / 2; |
| 52 | + if (latitude > midpoint) |
70 | 53 | {
|
71 |
| - currentBit++; |
| 54 | + base32Index |= 1 << (4 - currentBit); |
| 55 | + latitudeRange[0] = midpoint; |
72 | 56 | }
|
73 | 57 | else
|
74 | 58 | {
|
75 |
| - geohashResult.Append(Base32Characters[base32Index]); |
76 |
| - currentBit = 0; |
77 |
| - base32Index = 0; |
| 59 | + latitudeRange[1] = midpoint; |
78 | 60 | }
|
79 | 61 | }
|
80 | 62 |
|
81 |
| - return geohashResult.ToString(); |
| 63 | + isEncodingLongitude = !isEncodingLongitude; |
| 64 | + |
| 65 | + if (currentBit < 4) |
| 66 | + { |
| 67 | + currentBit++; |
| 68 | + } |
| 69 | + else |
| 70 | + { |
| 71 | + geohashResult.Append(Base32Characters[base32Index]); |
| 72 | + currentBit = 0; |
| 73 | + base32Index = 0; |
| 74 | + } |
82 | 75 | }
|
| 76 | + |
| 77 | + return geohashResult.ToString(); |
83 | 78 | }
|
84 | 79 | }
|
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