Sunday, 21 June 2015

Searching Nepali Text

It was late 2007, I was trying to develop the system that could search queries and displays the result from huge Nepali archives. There were two problems:

1. How to get huge amount of Nepali text ?
2. How to make them searchable and search with high relevancy ?

 I developed some state machines (a simple, equivalent regular expression) that can able accumulate news archives from the web dumped of many news sources.  A sample machine  for Himal News Paper is here.


Fig. State machine that accumulates news of Himal Khabar.

The java source representation of the state machine is:

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/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

/**
 *
 * @author Santa
 */
public class Himal { 
    
    private boolean isNepali(char ch) {
        if (ch >= 0x900 && ch <= 0x97f) {
            return (true);
        } else if (ch == ',' || ch == '?' || ch=='!') {
            return (true);
        } else if (ch == ' ') {
            return (true);
        } else if (ch == '\n') {
            return (true);
        } else {
            return (false);
        }
    }
    
    private StringBuffer filterText(StringBuffer s){
        StringBuffer result = new StringBuffer();
        char ch;
        int state = 0;
        for(int i=0;i<s.length();i++){
            ch = s.charAt(i);
            if(ch==',' || ch=='?' || ch=='เคƒ'){
                if(state != 0){
                    result.append(ch);
                    result.append(" ");
                }
                state = 0;
            }
            else if(ch==' '){
                if(state != 0)
                    result.append(ch);
                state = 0;
            }             
            else{
                state = 1;
                result.append(ch);
            }
        }
        return(result);
    }
    
   private StringBuffer dfaHimal(StringBuffer buffer){
        StringBuffer result = new StringBuffer();       
        String tmp = "";
        int state = 1;
        char ch;
        for(int i=0;i<buffer.length();i++){
            ch = buffer.charAt(i);          
            switch(state){
                case 1:
                    if(ch=='=')
                        state = 2;
                    else
                        state = 1;                   
                    break;
                case 2:
                    if(ch=='"')
                        state = 3;                    
                    else
                        state = 1;
                    break;
                case 3:
                    if(ch=='"'){
                        if(tmp.equals("headline")||tmp.equals("articletext")||tmp.equals("intro"))                                                        
                            state = 4;      
                        else
                            state = 1;
                        tmp = "";
                    }                    
                    else{
                        tmp += ch;
                        state = 3;
                    }
                    break;  
                case 4: 
                    if(isNepali(ch))
                        result.append(ch);                    
                    if(ch=='<')
                        state = 5;
                    else
                        state = 4;
                    break;
                case 5:
                    if(ch=='>'){
                        if(tmp.equals("br")||tmp.equals("/p")||tmp.equals("/P")||tmp.equals("BR")||tmp.equals("/TABLE")){
                            result.append("\r\n44  ");
                            state = 4;
                        }
                        else if(tmp.equals("/div")){
                            result.append("\r\n");
                            state = 1;
                        }
                        else
                            state = 4;
                    }
                    else if(ch=='='){
                        state = 6;
                    }
                    else{
                        tmp += ch;
                        state = 5;
                    }
                    break;
                case 6:
                    if(ch=='"'){
                        tmp = "";
                        state = 7; 
                    }
                    else
                        state = 4;
                    break;
                case 7:
                    if(ch=='"'){
                        if(tmp.equals("headlines"))
                            return(result);
                        else
                            state = 5;                      
                    }
                    else{
                        tmp += ch;
                        state = 7;
                    }
            }
        }
        return(result);
    }
    
    public StringBuffer getNewsText(String file){
        StringBuffer result = new StringBuffer();
        StringBuffer buffer = new StringBuffer();
        FileReadWrite obj = new FileReadWrite();
        buffer = obj.readFile(file);     
        result = dfaHimal(buffer);
        return(result);
    }

}

It was the beginning of the searching system development.


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