kotlin-stdlib/kotlin.collections/allEqualBy

allEqualBy

inline fun <T, K> Array<out T>.allEqualBy(selector: (T) -> K): Boolean(source)

Returns true if all elements in the array yield the same value produced by the given selector function.

Returns true for an empty array.

The selector values are compared sequentially using structural equality (==), and all elements are considered equal by the selector value if the selector value of the first element equals the selector value of every subsequent element.

For selector values of floating-point types (Double, Float), NaN is considered equal to NaN, and -0.0 is considered not equal to 0.0, consistent with Double.equals and Float.equals.

Since Kotlin

2.4

Samples


fun main() { 
   //sampleStart 
   println(arrayOf<String>().allEqualBy { it.length }) // true
println(arrayOf("apple").allEqualBy { it.length }) // true

val values = arrayOf("apple", "mango", "peach")
println(values.allEqualBy { it.length }) // true
println(values.allEqualBy { it }) // false 
   //sampleEnd
}

@ExperimentalStdlibApi

inline fun <K> ByteArray.allEqualBy(selector: (Byte) -> K): Boolean(source)

Returns true if all elements in the array yield the same value produced by the given selector function.

Returns true for an empty array.

For selector values of floating-point types (Double, Float), NaN is considered equal to NaN, and -0.0 is considered not equal to 0.0, consistent with Double.equals and Float.equals.

Since Kotlin

2.4

Samples

import kotlin.math.abs

fun main() { 
   //sampleStart 
   println(byteArrayOf().allEqualBy { it * it }) // true
println(byteArrayOf(1).allEqualBy { it * it }) // true

val values = byteArrayOf(1, -1, 1)
println(values.allEqualBy { it * it }) // true
println(values.allEqualBy { abs(it.toInt()) }) // true
println(values.allEqualBy { it * it * it }) // false 
   //sampleEnd
}

@ExperimentalStdlibApi

inline fun <K> ShortArray.allEqualBy(selector: (Short) -> K): Boolean(source)

Returns true if all elements in the array yield the same value produced by the given selector function.

Returns true for an empty array.

For selector values of floating-point types (Double, Float), NaN is considered equal to NaN, and -0.0 is considered not equal to 0.0, consistent with Double.equals and Float.equals.

Since Kotlin

2.4

Samples

import kotlin.math.abs

fun main() { 
   //sampleStart 
   println(shortArrayOf().allEqualBy { it * it }) // true
println(shortArrayOf(1).allEqualBy { it * it }) // true

val values = shortArrayOf(1, -1, 1)
println(values.allEqualBy { it * it }) // true
println(values.allEqualBy { abs(it.toInt()) }) // true
println(values.allEqualBy { it * it * it }) // false 
   //sampleEnd
}

@ExperimentalStdlibApi

inline fun <K> IntArray.allEqualBy(selector: (Int) -> K): Boolean(source)

Returns true if all elements in the array yield the same value produced by the given selector function.

Returns true for an empty array.

For selector values of floating-point types (Double, Float), NaN is considered equal to NaN, and -0.0 is considered not equal to 0.0, consistent with Double.equals and Float.equals.

Since Kotlin

2.4

Samples

import kotlin.math.abs

fun main() { 
   //sampleStart 
   println(intArrayOf().allEqualBy { it * it }) // true
println(intArrayOf(1).allEqualBy { it * it }) // true

val values = intArrayOf(1, -1, 1)
println(values.allEqualBy { it * it }) // true
println(values.allEqualBy { abs(it) }) // true
println(values.allEqualBy { it * it * it }) // false 
   //sampleEnd
}

@ExperimentalStdlibApi

inline fun <K> LongArray.allEqualBy(selector: (Long) -> K): Boolean(source)

Returns true if all elements in the array yield the same value produced by the given selector function.

Returns true for an empty array.

For selector values of floating-point types (Double, Float), NaN is considered equal to NaN, and -0.0 is considered not equal to 0.0, consistent with Double.equals and Float.equals.

Since Kotlin

2.4

Samples

import kotlin.math.abs

fun main() { 
   //sampleStart 
   println(longArrayOf().allEqualBy { it * it }) // true
println(longArrayOf(1L).allEqualBy { it * it }) // true

val values = longArrayOf(1L, -1L, 1L)
println(values.allEqualBy { it * it }) // true
println(values.allEqualBy { abs(it) }) // true
println(values.allEqualBy { it * it * it }) // false 
   //sampleEnd
}

@ExperimentalStdlibApi

inline fun <K> FloatArray.allEqualBy(selector: (Float) -> K): Boolean(source)

Returns true if all elements in the array yield the same value produced by the given selector function.

Returns true for an empty array.

For selector values of floating-point types (Double, Float), NaN is considered equal to NaN, and -0.0 is considered not equal to 0.0, consistent with Double.equals and Float.equals.

Since Kotlin

2.4

Samples

import kotlin.math.abs

fun main() { 
   //sampleStart 
   println(floatArrayOf().allEqualBy { it * it }) // true
println(floatArrayOf(1.0f).allEqualBy { it * it }) // true

val values = floatArrayOf(1.0f, -1.0f, 1.0f)
println(values.allEqualBy { it * it }) // true
println(values.allEqualBy { abs(it) }) // true
println(values.allEqualBy { it * it * it }) // false 
   //sampleEnd
}

@ExperimentalStdlibApi

inline fun <K> DoubleArray.allEqualBy(selector: (Double) -> K): Boolean(source)

Returns true if all elements in the array yield the same value produced by the given selector function.

Returns true for an empty array.

For selector values of floating-point types (Double, Float), NaN is considered equal to NaN, and -0.0 is considered not equal to 0.0, consistent with Double.equals and Float.equals.

Since Kotlin

2.4

Samples

import kotlin.math.abs

fun main() { 
   //sampleStart 
   println(doubleArrayOf().allEqualBy { it * it }) // true
println(doubleArrayOf(1.0).allEqualBy { it * it }) // true

val values = doubleArrayOf(1.0, -1.0, 1.0)
println(values.allEqualBy { it * it }) // true
println(values.allEqualBy { abs(it) }) // true
println(values.allEqualBy { it * it * it }) // false 
   //sampleEnd
}

@ExperimentalStdlibApi

inline fun <K> BooleanArray.allEqualBy(selector: (Boolean) -> K): Boolean(source)

Returns true if all elements in the array yield the same value produced by the given selector function.

Returns true for an empty array.

For selector values of floating-point types (Double, Float), NaN is considered equal to NaN, and -0.0 is considered not equal to 0.0, consistent with Double.equals and Float.equals.

Since Kotlin

2.4

Samples


fun main() { 
   //sampleStart 
   println(booleanArrayOf().allEqualBy { 0 }) // true
println(booleanArrayOf(true).allEqualBy { 0 }) // true

val values = booleanArrayOf(true, false, true)
println(values.allEqualBy { 0 }) // true
println(values.allEqualBy { if (it) 1 else 0 }) // false 
   //sampleEnd
}

@ExperimentalStdlibApi

inline fun <K> CharArray.allEqualBy(selector: (Char) -> K): Boolean(source)

Returns true if all elements in the array yield the same value produced by the given selector function.

Returns true for an empty array.

For selector values of floating-point types (Double, Float), NaN is considered equal to NaN, and -0.0 is considered not equal to 0.0, consistent with Double.equals and Float.equals.

Since Kotlin

2.4

Samples


fun main() { 
   //sampleStart 
   println(charArrayOf().allEqualBy { it.uppercaseChar() }) // true
println(charArrayOf('a').allEqualBy { it.uppercaseChar() }) // true

val values = charArrayOf('a', 'A', 'a')
println(values.allEqualBy { it.uppercaseChar() }) // true
println(values.allEqualBy { it.lowercaseChar() }) // true
println(values.allEqualBy { it }) // false 
   //sampleEnd
}

@ExperimentalStdlibApi

inline fun <T, K> Iterable<T>.allEqualBy(selector: (T) -> K): Boolean(source)

Returns true if all elements in the collection yield the same value produced by the given selector function.

Returns true for an empty collection.

For selector values of floating-point types (Double, Float), NaN is considered equal to NaN, and -0.0 is considered not equal to 0.0, consistent with Double.equals and Float.equals.

Since Kotlin

2.4

Samples


fun main() { 
   //sampleStart 
   println(listOf<String>().allEqualBy { it.length }) // true
println(listOf("apple").allEqualBy { it.length }) // true

val values = listOf("apple", "mango", "peach")
println(values.allEqualBy { it.length }) // true
println(values.allEqualBy { it }) // false 
   //sampleEnd
}

@ExperimentalStdlibApi

@ExperimentalUnsignedTypes

inline fun <K> UIntArray.allEqualBy(selector: (UInt) -> K): Boolean(source)

Returns true if all elements in the array yield the same value produced by the given selector function.

Returns true for an empty array.

For selector values of floating-point types (Double, Float), NaN is considered equal to NaN, and -0.0 is considered not equal to 0.0, consistent with Double.equals and Float.equals.

Since Kotlin

2.4

Samples


fun main() { 
   //sampleStart 
   println(uintArrayOf().allEqualBy { it % 2u }) // true
println(uintArrayOf(1u).allEqualBy { it % 2u }) // true

val values = uintArrayOf(1u, 3u, 5u)
println(values.allEqualBy { it % 2u }) // true
println(values.allEqualBy { it }) // false 
   //sampleEnd
}

@ExperimentalStdlibApi

@ExperimentalUnsignedTypes

inline fun <K> ULongArray.allEqualBy(selector: (ULong) -> K): Boolean(source)

Returns true if all elements in the array yield the same value produced by the given selector function.

Returns true for an empty array.

For selector values of floating-point types (Double, Float), NaN is considered equal to NaN, and -0.0 is considered not equal to 0.0, consistent with Double.equals and Float.equals.

Since Kotlin

2.4

Samples


fun main() { 
   //sampleStart 
   println(ulongArrayOf().allEqualBy { it % 2uL }) // true
println(ulongArrayOf(1uL).allEqualBy { it % 2uL }) // true

val values = ulongArrayOf(1uL, 3uL, 5uL)
println(values.allEqualBy { it % 2uL }) // true
println(values.allEqualBy { it }) // false 
   //sampleEnd
}

@ExperimentalStdlibApi

@ExperimentalUnsignedTypes

inline fun <K> UByteArray.allEqualBy(selector: (UByte) -> K): Boolean(source)

Returns true if all elements in the array yield the same value produced by the given selector function.

Returns true for an empty array.

For selector values of floating-point types (Double, Float), NaN is considered equal to NaN, and -0.0 is considered not equal to 0.0, consistent with Double.equals and Float.equals.

Since Kotlin

2.4

Samples


fun main() { 
   //sampleStart 
   println(ubyteArrayOf().allEqualBy { it.toUInt() % 2u }) // true
println(ubyteArrayOf(1u).allEqualBy { it.toUInt() % 2u }) // true

val values = ubyteArrayOf(1u, 3u, 5u)
println(values.allEqualBy { it.toUInt() % 2u }) // true
println(values.allEqualBy { it }) // false 
   //sampleEnd
}

@ExperimentalStdlibApi

@ExperimentalUnsignedTypes

inline fun <K> UShortArray.allEqualBy(selector: (UShort) -> K): Boolean(source)

Returns true if all elements in the array yield the same value produced by the given selector function.

Returns true for an empty array.

For selector values of floating-point types (Double, Float), NaN is considered equal to NaN, and -0.0 is considered not equal to 0.0, consistent with Double.equals and Float.equals.

Since Kotlin

2.4

Samples


fun main() { 
   //sampleStart 
   println(ushortArrayOf().allEqualBy { it.toUInt() % 2u }) // true
println(ushortArrayOf(1u).allEqualBy { it.toUInt() % 2u }) // true

val values = ushortArrayOf(1u, 3u, 5u)
println(values.allEqualBy { it.toUInt() % 2u }) // true
println(values.allEqualBy { it }) // false 
   //sampleEnd
}

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