/*
* Apache License
* Version 2.0, January 2004
* http://www.apache.org/licenses/
*
* Copyright 2013 Aurelian Tutuianu
* Copyright 2014 Aurelian Tutuianu
* Copyright 2015 Aurelian Tutuianu
* Copyright 2016 Aurelian Tutuianu
*
* 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 rapaio.data.sample;
import rapaio.core.SamplingTools;
import rapaio.data.Frame;
import rapaio.data.Mapping;
import rapaio.data.Var;
import static rapaio.sys.WS.formatFlex;
/**
* Implements bootstrap row sampling (sampling with replacement)
*
* By default
* Created by <a href="mailto:padreati@yahoo.com">Aurelian Tutuianu</a> on 1/25/16.
*/
final class Bootstrap implements RowSampler {
private static final long serialVersionUID = -7987373317949449262L;
private final double percent;
public Bootstrap(double percent) {
this.percent = percent;
}
@Override
public Sample nextSample(Frame df, Var weights) {
Mapping map = Mapping.copy(SamplingTools.sampleWR(df.rowCount(), (int) (percent * df.rowCount())));
return new Sample(df.mapRows(map), weights.mapRows(map), map);
}
@Override
public String name() {
return "Bootstrap(p=" + formatFlex(percent) + ")";
}
}