/**
* Copyright 2009 DigitalPebble Ltd
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package com.digitalpebble.classification.libsvm;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Iterator;
import java.util.Map;
import com.digitalpebble.classification.Document;
import com.digitalpebble.classification.Lexicon;
import com.digitalpebble.classification.TrainingCorpus;
import com.digitalpebble.classification.Vector;
public class Utils {
/**
* Reads the output of the reader and delivers it at string.
*/
public static String readOutput(BufferedReader in) throws IOException {
StringBuffer output = new StringBuffer();
String line = "";
while ((line = in.readLine()) != null) {
output.append(line);
output.append("\n");
}
return output.toString();
}
public static File writeExamples(Document[] documents, Lexicon lexicon,
boolean create, String vector_location) throws IOException {
File vectorFile = new File(vector_location);
PrintWriter out = null;
out = new PrintWriter(new FileWriter(vectorFile));
for (int i = 0; i < documents.length; i++) {
Document doc = documents[i];
int label = doc.getLabel();
// get a vector from the document
// need a metric (e.g. relative frequency / binary)
// and a lexicon
// the vector is represented as a string directly
Vector vector = doc.getFeatureVector(lexicon);
out.print(label + " " + Utils.getVectorString(vector) + "\n");
}
out.close();
return vectorFile;
}
/**
* returns a vector i.e sequence of feature:value needs to have a pointer to
* the Lexicon used during the creation of the document here we generate the
* scores, taking into account the data in the lexicon
*/
private static String getVectorString(Vector vector) {
StringBuffer buffer = new StringBuffer();
int[] indices = vector.getIndices();
double[] values = vector.getValues();
for (int i = 0; i < indices.length; i++) {
buffer.append(" ").append(indices[i]).append(":").append(values[i]);
}
return buffer.toString();
}
public static File writeExamples(TrainingCorpus corpus, Lexicon lexicon,
boolean b, String vector_location) throws IOException {
return writeExamples(corpus, lexicon, b, vector_location, null, null);
}
public static File writeExamples(TrainingCorpus corpus, Lexicon lexicon,
boolean b, String vector_location,
Map<Integer, Integer> attributeMapping) throws IOException {
return writeExamples(corpus, lexicon, b, vector_location, null, null);
}
public static File writeExamples(TrainingCorpus corpus, Lexicon lexicon,
boolean b, String vector_location,
Map<Integer, Integer> attributeMapping, String format)
throws IOException {
if ("arff".equalsIgnoreCase(format))
return writeARFF(corpus, lexicon, b, vector_location,
attributeMapping);
return writeVectors(corpus, lexicon, b, vector_location,
attributeMapping);
}
public static File writeVectors(TrainingCorpus corpus, Lexicon lexicon,
boolean b, String vector_location,
Map<Integer, Integer> attributeMapping) throws IOException {
File vectorFile = new File(vector_location);
PrintWriter out = null;
out = new PrintWriter(new FileWriter(vectorFile));
// get an iterator on the Corpus
// and retrieve the documents one by one
Iterator<Document> docIterator = corpus.iterator();
while (docIterator.hasNext()) {
Document doc = docIterator.next();
int label = doc.getLabel();
// get a vector from the document
// need a metric (e.g. relative frequency / binary)
// and a lexicon
// the vector is represented as a string directly
Vector vector = null;
if (attributeMapping == null)
vector = doc.getFeatureVector(lexicon);
else
vector = doc.getFeatureVector(lexicon, attributeMapping);
out.print(label + " " + Utils.getVectorString(vector) + "\n");
}
out.close();
return vectorFile;
}
public static File writeARFF(TrainingCorpus corpus, Lexicon lexicon,
boolean b, String vector_location,
Map<Integer, Integer> attributeMapping) throws IOException {
File vectorFile = new File(vector_location);
PrintWriter out = null;
out = new PrintWriter(new FileWriter(vectorFile));
out.print("%\n% Dataset generated by the TextClassifiation API\n%\n\n");
// generate the arff headers
out.print("@relation dataset\n\n");
// label values
out.print("@attribute label {");
boolean isFirst=true;
for (String l:lexicon.getLabels()){
if (!isFirst)out.print(",");
out.print(l);
isFirst=false;
}
out.print("}\n");
// dump the content of the lexicon file
int attributeNum = lexicon.getAttributesNum();
Map<Integer, String> iindex = lexicon.getInvertedIndex();
for (int c = 1; c <= attributeNum; c++) {
String attrib = iindex.get(c);
if (attrib == null)
attrib = "NULL";
else
attrib = attrib.replaceAll("\\s+", " ");
attrib = attrib.replaceAll("\"", ""e;");
if (attrib.endsWith("\\"))
attrib = attrib.substring(0, attrib.length() - 1);
attrib = "\"i_" + c + "_" + attrib + "\"";
out.print("@attribute " + attrib + " NUMERIC\n");
}
out.print("\n");
out.print("@data\n");
// get an iterator on the Corpus
// and retrieve the documents one by one
Iterator<Document> docIterator = corpus.iterator();
while (docIterator.hasNext()) {
Document doc = docIterator.next();
int label = doc.getLabel();
// get a vector from the document
// need a metric (e.g. relative frequency / binary)
// and a lexicon
// the vector is represented as a string directly
Vector vector = null;
if (attributeMapping == null)
vector = doc.getFeatureVector(lexicon);
else
vector = doc.getFeatureVector(lexicon, attributeMapping);
StringBuffer buffer = new StringBuffer("{");
buffer.append("0 ").append(lexicon.getLabel(label));
// {1 X, 3 Y, 4 "class A"}
// index space value
int[] indices = vector.getIndices();
double[] values = vector.getValues();
for (int i = 0; i < indices.length; i++) {
if (buffer.length() > 1)
buffer.append(", ");
if (indices[i] > attributeNum)
continue;
buffer.append(indices[i]).append(" ").append(values[i]);
}
buffer.append("}\n");
out.print(buffer.toString());
}
out.close();
return vectorFile;
}
}