org.tensorics.core.function.MathFunctions.java Source code

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Here is the source code for org.tensorics.core.function.MathFunctions.java

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// @formatter:off
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* This file is part of tensorics.
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* Copyright (c) 2008-2016, CERN. All rights reserved.
*
* 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
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* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
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// @formatter:on
package org.tensorics.core.function;

import java.util.Collection;
import java.util.Comparator;
import java.util.stream.Collectors;

import org.tensorics.core.commons.operations.Conversion;
import org.tensorics.core.function.interpolation.InterpolationStrategy;
import org.tensorics.core.lang.Tensorics;
import org.tensorics.core.reduction.ToFunctions;
import org.tensorics.core.tensor.Tensor;

import com.google.common.base.Preconditions;

/**
 * Provides utility method for transforming {@link MathFunction}s
 * 
 * @author caguiler, kfuchsbe
 */
public class MathFunctions {

    public static <X, Y> Tensor<DiscreteFunction<X, Y>> functionsFrom(Tensor<Y> tensor, Class<X> dimensionClass) {
        Preconditions.checkArgument(tensor.shape().dimensionality() >= 1,
                "tensor must contain at least one dimension");
        return Tensorics.from(tensor).reduce(dimensionClass).by(new ToFunctions<>());
    }

    public static <X, Y> DiscreteFunction<X, Y> functionFrom1DTensor(Tensor<Y> tensor, Class<X> dimensionClass) {
        Preconditions.checkArgument(tensor.shape().dimensionality() == 1, "tensor must be one-dimensional");
        return functionsFrom(tensor, dimensionClass).get();
    }

    public static <X, Y> InterpolatedFunction<X, Y> interpolated(DiscreteFunction<X, Y> function,
            InterpolationStrategy<Y> strategy, Conversion<X, Y> conversion, Comparator<X> comparator) {
        return new DefaultInterpolatedFunction<>(function, strategy, conversion, comparator);
    }

    public static <X, Y> Collection<Y> yValuesOf(DiscreteFunction<X, Y> function) {
        Preconditions.checkNotNull(function, "function cannot be null!");
        return function.definedXValues().stream().map(function::apply).collect(Collectors.toList());
    }
}