kitecore/io.github.yuroyami.kitecore.structures/Counter

Counter

class Counter<T> : Iterable<Map.Entry<T, Int>>

A multiset that tracks how many times each element has been added.

Counts are always positive; removing an element down to zero deletes its key, and querying an absent element yields zero. Iteration and toMap follow first-insertion order. mostCommon sorts by count descending and breaks ties by first-insertion order. Backed by LinkedHashMap.

This class is not thread-safe.

Type Parameters

the element type.

Constructors

Counter

constructor()

Properties

total

val total: Int

The sum of the counts of all elements.

Functions

add

fun add(element: T, count: Int = 1)

Increases the count of element by count.

allEqual

fun <T> Iterable<T>.allEqual(): Boolean

Returns true when every element equals the first one. An empty iterable returns true.

anyDuplicate

fun <T> Iterable<T>.anyDuplicate(): Boolean

Returns true if at least one element occurs more than once.

associateWithIndex

fun <T> Iterable<T>.associateWithIndex(): Map<T, Int>

Returns a map of each element to its index in this iterable.

average

fun Iterable<Duration>.average(): Duration

Returns the average of all durations.

cartesianProduct

fun <T, R> Iterable<T>.cartesianProduct(other: Iterable<R>): List<Pair<T, R>>

Returns every pairing of an element of this iterable with an element of other.

chunkedBy

inline fun <T, K> Iterable<T>.chunkedBy(selector: (T) -> K): List<List<T>>

Splits this iterable into consecutive runs, starting a new run whenever the value of selector changes.

clear

fun clear()

Removes every element and resets total to zero.

count

fun count(element: T): Int

Returns the count of element, or 0 if it is absent.

countBy

inline fun <T, K> Iterable<T>.countBy(selector: (T) -> K): Map<K, Int>

Returns a map of each distinct value of selector to the number of elements producing it.

duplicates

fun <T> Iterable<T>.duplicates(): Set<T>

Returns the set of elements that occur more than once.

frequencies

fun <T> Iterable<T>.frequencies(): Map<T, Int>

Returns a map of each distinct element to the number of times it occurs.

isDistinct

fun <T> Iterable<T>.isDistinct(): Boolean

Returns true if no element occurs more than once.

iterator

open operator override fun iterator(): Iterator<Map.Entry<T, Int>>

Returns an iterator over a snapshot of the entries in first-insertion order. Mutating the counter after this call does not affect the iterator.

mapToSet

inline fun <T, R> Iterable<T>.mapToSet(transform: (T) -> R): Set<R>

Returns a set of the results of applying transform to each element.

minMaxOrNull

fun <T : Comparable<T>> Iterable<T>.minMaxOrNull(): Pair<T, T>?

Returns the smallest and largest element as a pair, or null if the receiver is empty.

mode

fun <T> Iterable<T>.mode(): T?

Returns the most frequent element, or null if the receiver is empty.

mostCommon

fun mostCommon(n: Int = Int.MAX_VALUE): List<Pair<T, Int>>

Returns up to n elements with their counts, highest count first.

parallelFilter

suspend fun <T> Iterable<T>.parallelFilter(concurrency: Int = Int.MAX_VALUE, predicate: suspend (T) -> Boolean): List<T>

Evaluates predicate for every element concurrently and returns the matching elements in the original order.

parallelFilterNot

suspend fun <T> Iterable<T>.parallelFilterNot(concurrency: Int = Int.MAX_VALUE, predicate: suspend (T) -> Boolean): List<T>

Evaluates predicate for every element concurrently and returns the non-matching elements in the original order.

parallelFlatMap

suspend fun <T, R> Iterable<T>.parallelFlatMap(concurrency: Int = Int.MAX_VALUE, transform: suspend (T) -> Iterable<R>): List<R>

Transforms every element concurrently and returns the flattened results in the original order.

parallelForEach

suspend fun <T> Iterable<T>.parallelForEach(concurrency: Int = Int.MAX_VALUE, action: suspend (T) -> Unit)

Runs action for every element concurrently and returns when all have finished.

parallelForEachIndexed

suspend fun <T> Iterable<T>.parallelForEachIndexed(concurrency: Int = Int.MAX_VALUE, action: suspend (index: Int, element: T) -> Unit)

Runs action for every element with its index concurrently and returns when all have finished.

parallelMap

suspend fun <T, R> Iterable<T>.parallelMap(concurrency: Int = Int.MAX_VALUE, transform: suspend (T) -> R): List<R>

Transforms every element concurrently and returns the results in the original order.

parallelMapIndexed

suspend fun <T, R> Iterable<T>.parallelMapIndexed(concurrency: Int = Int.MAX_VALUE, transform: suspend (index: Int, element: T) -> R): List<R>

Transforms every element with its index concurrently and returns the results in the original order.

parallelMapIndexedNotNull

suspend fun <T, R : Any> Iterable<T>.parallelMapIndexedNotNull(concurrency: Int = Int.MAX_VALUE, transform: suspend (index: Int, element: T) -> R?): List<R>

Transforms every element with its index concurrently and returns the non-null results in the original order.

parallelMapNotNull

suspend fun <T, R : Any> Iterable<T>.parallelMapNotNull(concurrency: Int = Int.MAX_VALUE, transform: suspend (T) -> R?): List<R>

Transforms every element concurrently and returns the non-null results in the original order.

partitionIndexed

inline fun <T> Iterable<T>.partitionIndexed(predicate: (index: Int, T) -> Boolean): Pair<List<T>, List<T>>

Splits this iterable into a pair of lists using predicate, which also receives each element's index.

plusAssign

operator fun plusAssign(element: T)

Increases the count of element by one. Shorthand for add.

product

@JvmName(name = "productOfDouble")

fun Iterable<Double>.product(): Double

@JvmName(name = "productOfLong")

fun Iterable<Long>.product(): Long

Returns the product of all elements.

@JvmName(name = "productOfInt")

fun Iterable<Int>.product(): Long

Returns the product of all elements, accumulated as a Long.

remove

fun remove(element: T, count: Int = 1)

Decreases the count of element by count, flooring at zero.

splitBy

inline fun <T> Iterable<T>.splitBy(isDelimiter: (T) -> Boolean): List<List<T>>

Splits this iterable into segments separated by elements matching isDelimiter, dropping the delimiters.

sum

fun Iterable<Duration>.sum(): Duration

Returns the sum of all durations, or Duration.ZERO for an empty iterable.

toMap

fun toMap(): Map<T, Int>

Returns a snapshot of the counts in first-insertion order.

useAll

inline fun <T> Iterable<AutoCloseable>.useAll(block: () -> T): T

Runs block and then closes every resource in this collection in reverse iteration order.