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Evaluating random generators using compression algorithm : less compressed meaning better random generator ? / published by https://github.com/dacr/code-examples-manager #12596664-b528-404b-9e34-ec4e856e019d/289ffa17d0ba41679e1a3a19af05aab12c885a64
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// summary : Evaluating random generators using compression algorithm : less compressed meaning better random generator ? | |
// keywords : scala, random, rng, @testable | |
// publish : gist | |
// authors : David Crosson | |
// license : Proprietary BUT Machine Learning models training is not allowed by the author | |
// id : 12596664-b528-404b-9e34-ec4e856e019d | |
// created-on : 2022-02-26T08:08:12+01:00 | |
// managed-by : https://github.com/dacr/code-examples-manager | |
// run-with : scala-cli $file | |
// --------------------- | |
//> using scala "3.2.2" | |
//> using dep "org.apache.commons:commons-compress:1.23.0" | |
//> using dep "org.tukaani:xz:1.9" | |
// --------------------- | |
import org.apache.commons.compress.compressors.bzip2.BZip2CompressorOutputStream | |
import org.apache.commons.compress.compressors.xz.XZCompressorOutputStream | |
import org.apache.commons.compress.compressors.gzip.GzipCompressorOutputStream | |
import java.io.{ByteArrayOutputStream, OutputStream} | |
import java.nio.ByteBuffer | |
import scala.Console.{BLUE, GREEN, YELLOW, RED, RESET} | |
object RandomGenerators: | |
trait RandomGenerator: | |
def nextInt(n: Int): Int | |
class DefaultRandom(seed: Long = System.currentTimeMillis()) extends RandomGenerator: | |
private val random = scala.util.Random(seed) | |
final def nextInt(n: Int): Int = random.nextInt(n) | |
class BasicFastRandom(seed: Long = System.currentTimeMillis()) extends RandomGenerator: | |
private var g_seed = (seed >> 16 & 0x7fffffff).toInt | |
final def nextInt(n: Int) = | |
g_seed = 214013 * g_seed + 2531011 | |
((g_seed >> 16) & 0x7fff) % n | |
class XORShift32(val seed: Long = System.currentTimeMillis()) extends RandomGenerator: | |
private var cseed = seed | |
private def randomInt = | |
var x = cseed | |
x ^= (x << 13) | |
x ^= (x >>> 17) | |
x ^= (x << 5) | |
cseed = x | |
x | |
final def nextInt(bound: Int): Int = ((randomInt & 0x7fffff) % bound).toInt | |
object Compressors: | |
def compress(makeCompressorOutputStream: OutputStream => OutputStream)(input: Array[Byte]): Array[Byte] = | |
val baos = new ByteArrayOutputStream() | |
val outputStream = makeCompressorOutputStream(baos) | |
try outputStream.write(input) | |
finally if (outputStream != null) outputStream.close() | |
baos.toByteArray | |
def now() = System.currentTimeMillis | |
case class RandomCheckResult(name: String, compressedLevel: Double, randomGenerationDuration: Long, compressorDuration: Long): | |
override def toString = f"$BLUE$name$RESET : $compressedLevel%.2f%% in $randomGenerationDuration%sms $compressorDuration%sms" | |
object RandomChecks: | |
def randomCheck( | |
name: String, | |
nextInt: Int => Int, | |
compressor: Array[Byte] => Array[Byte], | |
bound: Int = 32 | |
): RandomCheckResult = | |
val bytesCount = 5 * 1024 * 1024 | |
val rngStarted = now() | |
val input = LazyList.continually(nextInt(bound)).map(_.toByte).take(bytesCount).toArray | |
val rngDuration = now() - rngStarted | |
val compressorStarted = now() | |
val output = compressor(input) | |
val compressorDuration = now() - compressorStarted | |
val result = 100d * output.size / input.size | |
RandomCheckResult(name, result, rngDuration, compressorDuration) | |
val compressor = Compressors.compress(out => XZCompressorOutputStream(out)) | |
//val compressor = Compressors.compress(out => BZip2CompressorOutputStream(out)) | |
//val compressor = Compressors.compress(out => GzipCompressorOutputStream(out)) | |
//val seed = System.currentTimeMillis | |
val seed = 42 | |
val bound = 2 | |
println(s"${GREEN}USING COMPRESSION ALGORITHM TO EVALUATE RANDOM GENERATORS$RESET") | |
println(s" $YELLOW(Higher is better)$RESET") | |
val algos: List[(String, Int => Int)] = List( | |
"NOT-RANDOM" -> (_ => 42), | |
"DEFAULT" -> RandomGenerators.DefaultRandom(seed).nextInt, | |
"BASICFAST" -> RandomGenerators.BasicFastRandom(seed).nextInt, | |
"XORSHIFT32" -> RandomGenerators.XORShift32(seed).nextInt | |
) | |
algos | |
.map((name, nextInt) => RandomChecks.randomCheck(name, nextInt, compressor, bound)) | |
.sortBy(_.compressedLevel) | |
.map(println) |
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