{"id":4998,"date":"2013-06-14T00:28:45","date_gmt":"2013-06-13T22:28:45","guid":{"rendered":"http:\/\/www.palentino.es\/blog\/?p=4998"},"modified":"2013-06-14T10:01:31","modified_gmt":"2013-06-14T08:01:31","slug":"el-algoritmo-de-pagerank-al-detalle","status":"publish","type":"post","link":"https:\/\/www.palentino.es\/blog\/el-algoritmo-de-pagerank-al-detalle\/","title":{"rendered":"El algoritmo de PageRank de google al detalle."},"content":{"rendered":"

Os dejo el c\u00f3digo fuente realizado en C# del algoritmo de c\u00e1lculo de Pagerank de un sitio de google.<\/p>\n

Pod\u00e9is compilarlo, generar una DLL y usarlo en cualquier proyecto . NET que necesit\u00e9is independientemente del lenguaje usado.<\/p>\n

Este es el c\u00f3digo al detalle.<\/p>\n

<\/p>\n

El programa ejecutable, lo pod\u00e9is descargar desde aqu\u00ed.\u00a0PageRank<\/a>\u00a0<\/strong>by Palentino.<\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

using System;<\/span><\/pre>\n
 using System.IO;<\/span><\/pre>\n
using System.Net;<\/span><\/pre>\n
using System.Text;<\/span><\/pre>\n
public class GooglePageRank<\/span>\r\n {<\/span>\r\n \/\/\/<\/span>\r\n \/\/\/ Devuelve el PageRank una URL suministrada. 0 a 10 \u00f3<\/span>\r\n \/\/\/ -1 (N\/A), que indica que ha existido un error<\/span>\r\n \/\/\/ o la URL no esta indexada.<\/span>\r\n \/\/\/<\/span>\r\n \/\/\/URL a testear<\/span>\r\n \/\/\/<\/span>\r\n public static int GetPageRank(string url)<\/span>\r\n {<\/span>\r\n int rank = -1;<\/span><\/pre>\n
try<\/span>\r\n {<\/span>\r\n \/\/ URL a completar<\/span>\r\n url = String.Format(\"http:\/\/toolbarqueries.google.com\/tbr\" +<\/span>\r\n \"?client=navclient-auto&features=Rank&ch={0}&q=info:{1}\",<\/span>\r\n ComputeHash(url), UrlEncode(url));<\/span><\/pre>\n
\/\/ P\u00e1gina de descarga<\/span>\r\n HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);<\/span>\r\n StreamReader stream = new StreamReader(request.GetResponse().GetResponseStream());<\/span>\r\n string response = stream.ReadToEnd();<\/span><\/pre>\n
\/\/ P\u00e1gina de page rank a parsear<\/span>\r\n string[] arr = response.Split(':');<\/span>\r\n if (arr.Length == 3)<\/span>\r\n rank = int.Parse(arr[2]);<\/span>\r\n }<\/span>\r\n catch (Exception)<\/span>\r\n {<\/span>\r\n \/\/ No hace nada, pero retorna un -1;<\/span>\r\n }<\/span>\r\n return rank;<\/span>\r\n }<\/span><\/pre>\n
\/\/\/<\/span>\r\n \/\/\/ URL-encodea la URL dada. \u00datil cuando HttpUtility no est\u00e1 disponible<\/span>\r\n \/\/\/<\/span>\r\n \/\/\/URL a encodear<\/span>\r\n \/\/\/<\/span>\r\n private static string UrlEncode(string url)<\/span>\r\n {<\/span>\r\n StringBuilder builder = new StringBuilder();<\/span><\/pre>\n
foreach (char c in url)<\/span>\r\n {<\/span>\r\n if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || (c >= '0' && c <= '9'))<\/span>\r\n builder.Append(c);<\/span>\r\n else if (c == ' ')<\/span>\r\n builder.Append('+');<\/span>\r\n else if (\"()*-_.!\".IndexOf(c) >= 0)<\/span>\r\n builder.Append(c);<\/span>\r\n else<\/span>\r\n builder.AppendFormat(\"%{0:X2}\", (byte)c);<\/span>\r\n }<\/span>\r\n return builder.ToString();<\/span>\r\n }<\/span><\/pre>\n
\/\/\/<\/span>\r\n \/\/\/ Calcula un valor hash requerido por Google<\/span>\r\n \/\/\/<\/span>\r\n private static string ComputeHash(string url)<\/span>\r\n {<\/span>\r\n UInt32 a, b;<\/span>\r\n UInt32 c = 0xE6359A60;<\/span>\r\n int k = 0;<\/span>\r\n int len;<\/span><\/pre>\n
\/\/ Modifica la URL<\/span>\r\n url = string.Format(\"info:{0}\", url);<\/span><\/pre>\n
a = b = 0x9E3779B9;<\/span>\r\n len = url.Length;<\/span><\/pre>\n
while (len >= 12)<\/span>\r\n {<\/span>\r\n a += (UInt32)(url[k + 0] + (url[k + 1] << 8) + (url[k + 2] << 16) + (url[k + 3] << 24));<\/span>\r\n b += (UInt32)(url[k + 4] + (url[k + 5] << 8) + (url[k + 6] << 16) + (url[k + 7] << 24));<\/span>\r\n c += (UInt32)(url[k + 8] + (url[k + 9] << 8) + (url[k + 10] << 16) + (url[k + 11] << 24));<\/span>\r\n Mix(ref a, ref b, ref c);<\/span>\r\n k += 12;<\/span>\r\n len -= 12;<\/span>\r\n }<\/span><\/pre>\n
c += (UInt32)url.Length;<\/span>\r\n switch (len)<\/span>\r\n {<\/span>\r\n case 11:<\/span>\r\n c += (UInt32)(url[k + 10] << 24);<\/span>\r\n goto case 10;<\/span>\r\n case 10:<\/span>\r\n c += (UInt32)(url[k + 9] << 16);<\/span>\r\n goto case 9;<\/span>\r\n case 9:<\/span>\r\n c += (UInt32)(url[k + 8] << 8);<\/span>\r\n goto case 8;<\/span>\r\n case 8:<\/span>\r\n b += (UInt32)(url[k + 7] << 24);<\/span>\r\n goto case 7;<\/span>\r\n case 7:<\/span>\r\n b += (UInt32)(url[k + 6] << 16);<\/span>\r\n goto case 6;<\/span>\r\n case 6:<\/span>\r\n b += (UInt32)(url[k + 5] << 8);<\/span>\r\n goto case 5;<\/span>\r\n case 5:<\/span>\r\n b += (UInt32)(url[k + 4]);<\/span>\r\n goto case 4;<\/span>\r\n case 4:<\/span>\r\n a += (UInt32)(url[k + 3] << 24);<\/span>\r\n goto case 3;<\/span>\r\n case 3:<\/span>\r\n a += (UInt32)(url[k + 2] << 16);<\/span>\r\n goto case 2;<\/span>\r\n case 2:<\/span>\r\n a += (UInt32)(url[k + 1] << 8);<\/span>\r\n goto case 1;<\/span>\r\n case 1:<\/span>\r\n a += (UInt32)(url[k + 0]);<\/span>\r\n break;<\/span>\r\n default:<\/span>\r\n break;<\/span>\r\n }<\/span>\r\n Mix(ref a, ref b, ref c);<\/span>\r\n return string.Format(\"6{0}\", c);<\/span>\r\n }<\/span>\r\n \/\/\/<\/span>\r\n \/\/\/ ComputeHash() m\u00e9todo de ayuda<\/span>\r\n \/\/\/<\/span>\r\n private static void Mix(ref UInt32 a, ref UInt32 b, ref UInt32 c)<\/span>\r\n {<\/span>\r\n a -= b; a -= c; a ^= c >> 13;<\/span>\r\n b -= c; b -= a; b ^= a << 8;<\/span>\r\n c -= a; c -= b; c ^= b >> 13;<\/span>\r\n a -= b; a -= c; a ^= c >> 12;<\/span>\r\n b -= c; b -= a; b ^= a << 16;<\/span>\r\n c -= a; c -= b; c ^= b >> 5;<\/span>\r\n a -= b; a -= c; a ^= c >> 3;<\/span>\r\n b -= c; b -= a; b ^= a << 10;<\/span>\r\n c -= a; c -= b; c ^= b >> 15;<\/span>\r\n }<\/span>\r\n }\r\n\r\nC\u00f3digo en formato .txt -> PageRank\r\n\r\n<\/a><\/span><\/strong><\/span><\/span><\/pre>\n","protected":false},"excerpt":{"rendered":"
Os dejo el c\u00f3digo fuente realizado en C# del algoritmo de c\u00e1lculo de Pagerank de un sitio de google. Pod\u00e9is compilarlo, generar una DLL y usarlo en cualquier proyecto . NET que necesit\u00e9is independientemente del lenguaje usado. Este es el c\u00f3digo al detalle.<\/p>\n","protected":false},"author":1,"featured_media":2483,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9,14],"tags":[669,428,659],"class_list":["post-4998","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-seo","category-varios","tag-google","tag-pagerank","tag-seo"],"_links":{"self":[{"href":"https:\/\/www.palentino.es\/blog\/wp-json\/wp\/v2\/posts\/4998","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.palentino.es\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.palentino.es\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.palentino.es\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.palentino.es\/blog\/wp-json\/wp\/v2\/comments?post=4998"}],"version-history":[{"count":15,"href":"https:\/\/www.palentino.es\/blog\/wp-json\/wp\/v2\/posts\/4998\/revisions"}],"predecessor-version":[{"id":5020,"href":"https:\/\/www.palentino.es\/blog\/wp-json\/wp\/v2\/posts\/4998\/revisions\/5020"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.palentino.es\/blog\/wp-json\/wp\/v2\/media\/2483"}],"wp:attachment":[{"href":"https:\/\/www.palentino.es\/blog\/wp-json\/wp\/v2\/media?parent=4998"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.palentino.es\/blog\/wp-json\/wp\/v2\/categories?post=4998"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.palentino.es\/blog\/wp-json\/wp\/v2\/tags?post=4998"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}