org.apache.mahout.classifier.df.data.Data Maven / Gradle / Ivy
/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.mahout.classifier.df.data;
import org.apache.mahout.classifier.df.data.conditions.Condition;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.List;
import java.util.Random;
/**
* Holds a list of vectors and their corresponding Dataset. contains various operations that deals with the
* vectors (subset, count,...)
*
*/
public class Data implements Cloneable {
private final List instances;
private final Dataset dataset;
public Data(Dataset dataset) {
this.dataset = dataset;
this.instances = new ArrayList<>();
}
public Data(Dataset dataset, List instances) {
this.dataset = dataset;
this.instances = new ArrayList<>(instances);
}
/**
* @return the number of elements
*/
public int size() {
return instances.size();
}
/**
* @return true if this data contains no element
*/
public boolean isEmpty() {
return instances.isEmpty();
}
/**
* @param v
* element whose presence in this list if to be searched
* @return true is this data contains the specified element.
*/
public boolean contains(Instance v) {
return instances.contains(v);
}
/**
* Returns the element at the specified position
*
* @param index
* index of element to return
* @return the element at the specified position
* @throws IndexOutOfBoundsException
* if the index is out of range
*/
public Instance get(int index) {
return instances.get(index);
}
/**
* @return the subset from this data that matches the given condition
*/
public Data subset(Condition condition) {
List subset = new ArrayList<>();
for (Instance instance : instances) {
if (condition.isTrueFor(instance)) {
subset.add(instance);
}
}
return new Data(dataset, subset);
}
/**
* if data has N cases, sample N cases at random -but with replacement.
*/
public Data bagging(Random rng) {
int datasize = size();
List bag = new ArrayList<>(datasize);
for (int i = 0; i < datasize; i++) {
bag.add(instances.get(rng.nextInt(datasize)));
}
return new Data(dataset, bag);
}
/**
* if data has N cases, sample N cases at random -but with replacement.
*
* @param sampled
* indicating which instance has been sampled
*
* @return sampled data
*/
public Data bagging(Random rng, boolean[] sampled) {
int datasize = size();
List bag = new ArrayList<>(datasize);
for (int i = 0; i < datasize; i++) {
int index = rng.nextInt(datasize);
bag.add(instances.get(index));
sampled[index] = true;
}
return new Data(dataset, bag);
}
/**
* Splits the data in two, returns one part, and this gets the rest of the data. VERY SLOW!
*/
public Data rsplit(Random rng, int subsize) {
List subset = new ArrayList<>(subsize);
for (int i = 0; i < subsize; i++) {
subset.add(instances.remove(rng.nextInt(instances.size())));
}
return new Data(dataset, subset);
}
/**
* checks if all the vectors have identical attribute values
*
* @return true is all the vectors are identical or the data is empty
* false otherwise
*/
public boolean isIdentical() {
if (isEmpty()) {
return true;
}
Instance instance = get(0);
for (int attr = 0; attr < dataset.nbAttributes(); attr++) {
for (int index = 1; index < size(); index++) {
if (get(index).get(attr) != instance.get(attr)) {
return false;
}
}
}
return true;
}
/**
* checks if all the vectors have identical label values
*/
public boolean identicalLabel() {
if (isEmpty()) {
return true;
}
double label = dataset.getLabel(get(0));
for (int index = 1; index < size(); index++) {
if (dataset.getLabel(get(index)) != label) {
return false;
}
}
return true;
}
/**
* finds all distinct values of a given attribute
*/
public double[] values(int attr) {
Collection result = new HashSet<>();
for (Instance instance : instances) {
result.add(instance.get(attr));
}
double[] values = new double[result.size()];
int index = 0;
for (Double value : result) {
values[index++] = value;
}
return values;
}
@Override
public Data clone() {
return new Data(dataset, new ArrayList<>(instances));
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (!(obj instanceof Data)) {
return false;
}
Data data = (Data) obj;
return instances.equals(data.instances) && dataset.equals(data.dataset);
}
@Override
public int hashCode() {
return instances.hashCode() + dataset.hashCode();
}
/**
* extract the labels of all instances
*/
public double[] extractLabels() {
double[] labels = new double[size()];
for (int index = 0; index < labels.length; index++) {
labels[index] = dataset.getLabel(get(index));
}
return labels;
}
/**
* finds the majority label, breaking ties randomly
* This method can be used when the criterion variable is the categorical attribute.
*
* @return the majority label value
*/
public int majorityLabel(Random rng) {
// count the frequency of each label value
int[] counts = new int[dataset.nblabels()];
for (int index = 0; index < size(); index++) {
counts[(int) dataset.getLabel(get(index))]++;
}
// find the label values that appears the most
return DataUtils.maxindex(rng, counts);
}
/**
* Counts the number of occurrences of each label value
* This method can be used when the criterion variable is the categorical attribute.
*
* @param counts
* will contain the results, supposed to be initialized at 0
*/
public void countLabels(int[] counts) {
for (int index = 0; index < size(); index++) {
counts[(int) dataset.getLabel(get(index))]++;
}
}
public Dataset getDataset() {
return dataset;
}
}