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Statistical sampling library for use in virtdata libraries, based on apache commons math 4

There is a newer version: 5.17.0

/*
 * Copyright (c) 2022 nosqlbench
 *
 * 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 io.nosqlbench.virtdata.library.curves4.continuous.common;

import io.nosqlbench.virtdata.library.curves4.discrete.common.ThreadSafeHash;

import java.util.function.DoubleUnaryOperator;
import java.util.function.LongToDoubleFunction;

public class RealLongDoubleSampler implements LongToDoubleFunction {

    private final DoubleUnaryOperator f;
    private final boolean clamp;
    private final double clampMax;
    private final double clampMin;
    private ThreadSafeHash hash;

    public RealLongDoubleSampler(DoubleUnaryOperator parentFunc, boolean hash, boolean clamp, double clampMin, double clampMax, boolean finite) {
        this.f = parentFunc;
        if (hash) {
            this.hash = new ThreadSafeHash();
        }
        this.clamp = clamp | finite;
        this.clampMin = Double.max(clampMin,Double.MIN_VALUE);
        this.clampMax = Double.min(clampMax,Double.MAX_VALUE);
    }

    @Override
    public double applyAsDouble(long value) {
        if (hash != null) {
            value = hash.applyAsLong(value);
        }
        double unit = (double) value / (double) Long.MAX_VALUE;
        double sample = clamp ? Double.max(clampMin, Double.min(clampMax, f.applyAsDouble(unit))) : f.applyAsDouble(unit);
        return sample;
    }
}