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/* Copyright (C) 2002 Univ. of Massachusetts Amherst, Computer Science Dept.
This file is part of "MALLET" (MAchine Learning for LanguagE Toolkit).
http://www.cs.umass.edu/~mccallum/mallet
This software is provided under the terms of the Common Public License,
version 1.0, as published by http://www.opensource.org. For further
information, see the file `LICENSE' included with this distribution. */
package cc.mallet.pipe;
import java.io.*;
import cc.mallet.types.Instance;
import cc.mallet.types.Token;
import cc.mallet.types.TokenSequence;
/**
Convert the string in each field Token.text to a list
of Strings (space delimited). Add each string as a feature to the
token. If realValued is true, then treat the position
in the list as the feature name and the value as a
double. Otherwise, the feature name is the string itself and the
value is 1.0.
Modified to allow feature names and values to be specified.eg:
featureName1=featureValue1 featureName2=featureValue2 ...
The name/value separator (here '=') can be specified.
* If your data consists of feature/value pairs (eg height=10.7 width=3.6 length=1.7),
* use new TokenSequenceParseFeatureString(true, true, "="). This
* format is typically used for sparse data, in which most features are equal to 0 in
* any given instance.
*
* If your data consists only of values, and the position determines which feature
* the value is for (eg 10.7 3.6 1.7),
* use new TokenSequenceParseFeatureString(true).
* This format is typically used for data that has a small number of features
* that all have non-zero values most of the time.
*
* If your data is in the form of named binary indicator variables
* (eg yellow quacks has_webbed_feet), use the constructor
* new TokenSequenceParseFeatureString(false). Each token will be
* interpreted as the name of a feature, whose value is 1.0.
@author Aron Culotta [email protected]
*/
public class TokenSequenceParseFeatureString extends Pipe implements Serializable
{
boolean realValued; // are these real-valued features?
boolean specifyFeatureNames; // are the feature names given as well?
String nameValueSeparator; // what separates the name from the value? (CAN'T BE WHITESPACE!)
/**
* @param _realValued interpret each data token as a double, and associate it with a
* feature called "Feature#K" where K is the order of the token, starting with 0.
* Note that this option is currently ignored if _specifyFeatureNames is true.
* @param _specifyFeatureNames interpret each data token as a feature name/value pair,
* separated by some delimiter, which is the equals sign ("=") unless otherwise specified.
* @param _nameValueSeparator use a string other than = to separate name/value pairs. Colon (":") is
* a common choice. Note that this string cannot consist of any whitespace, as the tokens stream
* will already have been split.
*/
public TokenSequenceParseFeatureString (boolean _realValued, boolean _specifyFeatureNames, String _nameValueSeparator) {
this.realValued = _realValued;
if (_nameValueSeparator.trim().length()==0) {
throw new IllegalArgumentException ("nameValueSeparator can't be whitespace");
}
nameValueSeparator = _nameValueSeparator;
this.specifyFeatureNames = _specifyFeatureNames;
}
public TokenSequenceParseFeatureString (boolean _realValued, boolean _specifyFeatureNames) {
this (_realValued, _specifyFeatureNames, "=");
}
public TokenSequenceParseFeatureString (boolean _realValued) {
this (_realValued, false, "=");
}
public Instance pipe (Instance carrier) {
TokenSequence ts = (TokenSequence) carrier.getData ();
for (int i=0; i < ts.size(); i++) {
Token t = ts.get (i);
String[] values = t.getText().split("\\s+");
for (int j=0; j < values.length; j++) {
if (specifyFeatureNames) {
String[] nameAndValue = values[j].split(nameValueSeparator);
if (nameAndValue.length != 2) { // no feature name. use token as feature.
t.setFeatureValue ("Token="+values[j], 1.0);
}
else {
t.setFeatureValue (nameAndValue[0], Double.parseDouble (nameAndValue[1]));
}
}
else if (realValued) {
t.setFeatureValue ("Feature#" + j, Double.parseDouble (values[j]));
}
else
t.setFeatureValue (values[j], 1.0);
}
}
carrier.setData (ts);
return carrier;
}
// Serialization
private static final long serialVersionUID = 1;
private static final int CURRENT_SERIAL_VERSION = 1;
private void writeObject (ObjectOutputStream out) throws IOException {
out.writeInt (CURRENT_SERIAL_VERSION);
out.writeBoolean (realValued);
out.writeBoolean (specifyFeatureNames);
out.writeObject (nameValueSeparator);
}
private void readObject (ObjectInputStream in) throws IOException, ClassNotFoundException {
int version = in.readInt ();
realValued = in.readBoolean ();
if (version >= CURRENT_SERIAL_VERSION) {
specifyFeatureNames = in.readBoolean();
nameValueSeparator = (String)in.readObject();
}
}
}