- added "did you mean" to search page

- currently works for single word queries only!

git-svn-id: https://svn.berlios.de/svnroot/repos/yacy/trunk@6057 6c8d7289-2bf4-0310-a012-ef5d649a1542

htroot/yacysearch.html

@@ -94,6 +94,10 @@ $(function() {
         <input type="hidden" name="constraint" value="#[constraint]#" />
       </fieldset>
     </form>
+    #(didYouMean)#
+	::
+    <p><b>Did you mean:</b> #{suggestions}# <a href="#[url]#">#[word]#</a> #[sep]##{/suggestions}#</p>
+    #(/didYouMean)#
 
 #(searchagain)#
 ::

htroot/yacysearch.java

@@ -29,6 +29,7 @@
 
 import java.io.IOException;
 import java.util.HashMap;
+import java.util.Iterator;
 import java.util.TreeSet;
 
 import de.anomic.content.RSSMessage;
@@ -53,6 +54,7 @@ import de.anomic.server.serverDomains;
 import de.anomic.server.serverObjects;
 import de.anomic.server.serverProfiling;
 import de.anomic.server.serverSwitch;
+import de.anomic.tools.DidYouMean;
 import de.anomic.tools.iso639;
 import de.anomic.tools.Formatter;
 import de.anomic.xml.RSSFeed;
@@ -85,7 +87,7 @@ public class yacysearch {
         String querystring = originalquerystring;
         boolean fetchSnippets = (post != null && post.get("verify", "false").equals("true"));
         final serverObjects prop = new serverObjects();
-        
+
         //final boolean rss = (post == null) ? false : post.get("rss", "false").equals("true");
         prop.put("promoteSearchPageGreeting", promoteSearchPageGreeting);
         prop.put("promoteSearchPageGreeting.homepage", sb.getConfig(plasmaSwitchboardConstants.GREETING_HOMEPAGE, ""));
@@ -465,6 +467,37 @@ public class yacysearch {
             theQuery.urlretrievaltime = theSearch.getURLRetrievalTime();
             theQuery.snippetcomputationtime = theSearch.getSnippetComputationTime();
             sb.localSearches.add(theQuery);
+                        
+            // check suggestions
+            DidYouMean didYouMean = new DidYouMean(sb);
+            Iterator<String> meanIt = didYouMean.getSuggestion(querystring).iterator();
+            int meanCount = 0;
+            String suggestion;
+            prop.put("didYouMean", 0);
+            while(meanIt.hasNext()) {
+            	suggestion = meanIt.next();
+            	prop.put("didYouMean_suggestions_"+meanCount+"_word", suggestion);
+            	prop.put("didYouMean_suggestions_"+meanCount+"_url",
+            		"/yacysearch.html" + "?display=" + display +
+	                "&search=" + suggestion +
+	                "&maximumRecords="+ theQuery.displayResults() +
+	                "&startRecord=" + (0 * theQuery.displayResults()) +
+	                "&resource=" + ((theQuery.isLocal()) ? "local" : "global") +
+	                "&verify=" + ((theQuery.onlineSnippetFetch) ? "true" : "false") +
+	                "&nav=" + theQuery.navigators +
+	                "&urlmaskfilter=" + originalUrlMask +
+	                "&prefermaskfilter=" + theQuery.prefer +
+	                "&cat=href&amp;constraint=" + ((theQuery.constraint == null) ? "" : theQuery.constraint.exportB64()) +
+	                "&contentdom=" + theQuery.contentdom() +
+	                "&former=" + theQuery.queryString(true)
+	             );
+            	prop.put("didYouMean_suggestions_"+meanCount+"_sep","|");
+            	meanCount++;
+            }
+            prop.put("didYouMean_suggestions_"+(meanCount-1)+"_sep","");
+            if(meanCount > 0)
+            	prop.put("didYouMean", 1);
+            prop.put("didYouMean_suggestions", meanCount);
             
             // update the search tracker
             try {
@@ -580,7 +613,7 @@ public class yacysearch {
         // for RSS: don't HTML encode some elements
         prop.putXML("rss_query", originalquerystring);
         prop.put("rss_queryenc", originalquerystring.replace(' ', '+'));
-
+                
         sb.localSearchLastAccess = System.currentTimeMillis();
         
         // return rewrite properties

source/de/anomic/tools/DidYouMean.java

@@ -0,0 +1,83 @@
+package de.anomic.tools;
+
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.Set;
+
+import de.anomic.plasma.plasmaSwitchboard;
+import de.anomic.plasma.parser.Word;
+
+// People make mistakes when they type words.  
+// The most common mistakes are the four categories listed below:
+// (1)	Changing one letter: bat / cat;
+// (2)	Adding one letter: bat / boat;
+// (3)	Deleting one letter: frog / fog; or
+// (4)	Reversing two consecutive letters: two / tow.
+
+public class DidYouMean {
+
+	private static char[] alphabet = {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p',
+									  'q','r','s','t','u','v','w','x','y','z','ä','ö','ü','ß'}; 
+	private final Set<String> set;
+	private String word;
+	private int len;
+	private final plasmaSwitchboard sb;
+	
+	public DidYouMean(final plasmaSwitchboard env) {
+		this.set = new HashSet<String>();
+		this.word = "";
+		this.len = 0;
+		this.sb = env;
+	}
+	
+	public Set<String> getSuggestion(String word) {
+		this.word = word.toLowerCase();
+		this.len = word.length();
+		ChangingOneLetter();
+		AddingOneLetter();
+		DeletingOneLetter();
+		ReversingTwoConsecutiveLetters();
+		Iterator<String> it = this.set.iterator();
+		String s;
+		final HashSet<String> rset = new HashSet<String>();
+		while(it.hasNext()) {
+			s = it.next();			
+			if(sb.indexSegment.termIndex().has(Word.word2hash(s))) {
+				rset.add(s);
+			}
+		}	
+		rset.remove(word.toLowerCase());
+		return rset;
+	}
+	
+	private void ChangingOneLetter() {		
+		for(int i=0; i<this.len; i++) {
+			for(int j=0; j<alphabet.length; j++) {
+				this.set.add(this.word.substring(0, i) + alphabet[j] + this.word.substring(i+1));
+			}
+		}
+	}
+	
+	private void DeletingOneLetter() {
+		for(int i=0; i<this.len;i++) {
+			this.set.add(this.word.substring(0, i) + this.word.substring(i+1));			
+		}
+	}
+	
+	private void AddingOneLetter() {
+		for(int i=0; i<this.len;i++) {
+			for(int j=0; j<alphabet.length; j++) {
+				this.set.add(this.word.substring(0, i) + alphabet[j] + this.word.substring(i));
+			}			
+		}
+	}
+	
+	private void ReversingTwoConsecutiveLetters() {
+		for(int i=0; i<this.word.length()-1; i++) {
+			this.set.add(this.word.substring(0,i)+this.word.charAt(i+1)+this.word.charAt(i)+this.word.substring(i+2));
+		}
+	}
+	
+}
+
+