Package com.github.tommyettinger.ds.support.sort

Class DoubleComparators

java.lang.Object

com.github.tommyettinger.ds.support.sort.DoubleComparators

public final class DoubleComparators
extends Object

A class providing static methods and objects that do useful things with comparators.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected static class	DoubleComparators.NaturalImplicitComparator	A type-specific comparator mimicking the natural order.
protected static class	DoubleComparators.OppositeComparator
protected static class	DoubleComparators.OppositeImplicitComparator	A type-specific comparator mimicking the opposite of the natural order.
protected static class	DoubleComparators.TolerantComparator

Field Summary

Fields

Modifier and Type	Field	Description
static final DoubleComparator	NATURAL_COMPARATOR
static final DoubleComparator	OPPOSITE_COMPARATOR
static final DoubleComparator	TOLERANT_COMPARATOR	A DoubleComparator using ascending order with a tolerance for equality of 0.000001.

Method Summary

Modifier and Type	Method	Description
static DoubleComparator	asDoubleComparator(Comparator<? super Double> c)	Returns a type-specific comparator that is equivalent to the given comparator.
static DoubleComparator	oppositeComparator(DoubleComparator c)	Returns a comparator representing the opposite order of the given comparator.
static void	sort(double[] items, int from, int to, DoubleComparator c)	Sorts the specified range of elements according to the order induced by the specified comparator using mergesort.
static void	sort(double[] items, DoubleComparator c)	Sorts all of items by simply calling sort(double[], int, int, DoubleComparator), setting from and to so the whole array is sorted.
static DoubleComparator	tolerantComparator(double tolerance)	Builds a new DoubleComparator, using ascending order with a tolerance for equality of tolerance.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

NATURAL_COMPARATOR

public static final DoubleComparator NATURAL_COMPARATOR

OPPOSITE_COMPARATOR

public static final DoubleComparator OPPOSITE_COMPARATOR

TOLERANT_COMPARATOR

public static final DoubleComparator TOLERANT_COMPARATOR

A DoubleComparator using ascending order with a tolerance for equality of 0.000001.

Method Details

oppositeComparator

public static DoubleComparator oppositeComparator(DoubleComparator c)

Returns a comparator representing the opposite order of the given comparator.

Parameters:

c - a comparator.

Returns:

a comparator representing the opposite order of c.

asDoubleComparator

public static DoubleComparator asDoubleComparator(Comparator<? super Double> c)

Returns a type-specific comparator that is equivalent to the given comparator.

Parameters:

c - a comparator, or null.

Returns:

a type-specific comparator representing the order of c.

tolerantComparator

public static DoubleComparator tolerantComparator(double tolerance)

Builds a new DoubleComparator, using ascending order with a tolerance for equality of tolerance. You can call its DoubleComparator.reversed() method to access a descending-order comparator.

Parameters:

tolerance - how much tolerance is acceptable when comparing two doubles as equal

Returns:

the new DoubleComparator

sort

public static void sort(double[] items,
 DoubleComparator c)

Sorts all of items by simply calling sort(double[], int, int, DoubleComparator), setting from and to so the whole array is sorted.

Parameters:

items - the double array to be sorted

c - a DoubleComparator to alter the sort order; if null, the natural order will be used

sort

public static void sort(double[] items,
 int from,
 int to,
 DoubleComparator c)

Sorts the specified range of elements according to the order induced by the specified comparator using mergesort.

This sort is guaranteed to be stable: equal elements will not be reordered as a result of the sort. The sorting algorithm is an in-place mergesort that is significantly slower than a standard mergesort, as its running time is O(n (log n)²), but it does not allocate additional memory; as a result, it can be used as a generic sorting algorithm.

If and only if c is null, this will delegate to Arrays.sort(double[], int, int), which does not have the same guarantees regarding allocation.

Parameters:

items - the double array to be sorted

from - the index of the first element (inclusive) to be sorted.

to - the index of the last element (exclusive) to be sorted.

c - a DoubleComparator to alter the sort order; if null, the natural order will be used