smile.projection.Projection Maven / Gradle / Ivy
/*******************************************************************************
* Copyright (c) 2010 Haifeng Li
*
* 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 smile.projection;
/**
* A projection is a kind of feature extraction technique that transforms data
* from the input space to a feature space, linearly or nonlinearly. Often,
* projections are used to reduce dimensionality, for example PCA and random
* projection. However, kernel-based methods, e.g. Kernel PCA, can actually map
* the data into a much higher dimensional space.
*
* @author Haifeng Li
*/
public interface Projection {
/**
* Project a data point to the feature space.
*/
public double[] project(T x);
/**
* Project a set of data toe the feature space.
*/
public double[][] project(T[] x);
}