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It is a library to compress and uncompress arrays of integers
very fast. The assumption is that most (but not all) values in
your array use less than 32 bits.
/**
* This code is released under the
* Apache License Version 2.0 http://www.apache.org/licenses/.
*
* (c) Daniel Lemire, http://lemire.me/en/
*/
package me.lemire.integercompression.benchmarktools;
import java.text.DecimalFormat;
import java.util.Arrays;
import java.util.Random;
import me.lemire.integercompression.BitPacking;
import me.lemire.integercompression.differential.Delta;
import me.lemire.integercompression.differential.IntegratedBitPacking;
/**
* Class used to benchmark the speed of bit packing. (For expert use.)
*
* @author Daniel Lemire
*
*/
public class BenchmarkBitPacking {
private static void test(boolean verbose) {
DecimalFormat dfspeed = new DecimalFormat("0");
final int N = 32;
final int times = 100000;
Random r = new Random(0);
int[] data = new int[N];
int[] compressed = new int[N];
int[] uncompressed = new int[N];
for (int bit = 0; bit < 31; ++bit) {
long comp = 0;
long compwm = 0;
long decomp = 0;
for (int t = 0; t < times; ++t) {
for (int k = 0; k < N; ++k) {
data[k] = r.nextInt(1 << bit);
}
long time1 = System.nanoTime();
BitPacking
.fastpack(data, 0, compressed, 0, bit);
long time2 = System.nanoTime();
BitPacking.fastpackwithoutmask(data, 0,
compressed, 0, bit);
long time3 = System.nanoTime();
BitPacking.fastunpack(compressed, 0,
uncompressed, 0, bit);
long time4 = System.nanoTime();
comp += time2 - time1;
compwm += time3 - time2;
decomp += time4 - time3;
}
if (verbose)
System.out.println("bit = "
+ bit
+ " comp. speed = "
+ dfspeed.format(N * times * 1000.0
/ (comp))
+ " comp. speed wm = "
+ dfspeed.format(N * times * 1000.0
/ (compwm))
+ " decomp. speed = "
+ dfspeed.format(N * times * 1000.0
/ (decomp)));
}
}
private static void testWithDeltas(boolean verbose) {
DecimalFormat dfspeed = new DecimalFormat("0");
final int N = 32;
final int times = 100000;
Random r = new Random(0);
int[] data = new int[N];
int[] compressed = new int[N];
int[] icompressed = new int[N];
int[] uncompressed = new int[N];
for (int bit = 1; bit < 31; ++bit) {
long comp = 0;
long decomp = 0;
long icomp = 0;
long idecomp = 0;
for (int t = 0; t < times; ++t) {
data[0] = r.nextInt(1 << bit);
for (int k = 1; k < N; ++k) {
data[k] = r.nextInt(1 << bit)
+ data[k - 1];
}
int[] tmpdata = Arrays
.copyOf(data, data.length);
long time1 = System.nanoTime();
Delta.delta(tmpdata);
BitPacking.fastpackwithoutmask(tmpdata, 0,
compressed, 0, bit);
long time2 = System.nanoTime();
BitPacking.fastunpack(compressed, 0,
uncompressed, 0, bit);
Delta.fastinverseDelta(uncompressed);
long time3 = System.nanoTime();
if (!Arrays.equals(data, uncompressed))
throw new RuntimeException("bug");
comp += time2 - time1;
decomp += time3 - time2;
tmpdata = Arrays.copyOf(data, data.length);
time1 = System.nanoTime();
IntegratedBitPacking.integratedpack(0, tmpdata,
0, icompressed, 0, bit);
time2 = System.nanoTime();
IntegratedBitPacking.integratedunpack(0,
icompressed, 0, uncompressed, 0, bit);
time3 = System.nanoTime();
if (!Arrays.equals(icompressed, compressed))
throw new RuntimeException("ibug "
+ bit);
if (!Arrays.equals(data, uncompressed))
throw new RuntimeException("bug " + bit);
icomp += time2 - time1;
idecomp += time3 - time2;
}
if (verbose)
System.out.println("bit = "
+ bit
+ " comp. speed = "
+ dfspeed.format(N * times * 1000.0
/ (comp))
+ " decomp. speed = "
+ dfspeed.format(N * times * 1000.0
/ (decomp))
+ " icomp. speed = "
+ dfspeed.format(N * times * 1000.0
/ (icomp))
+ " idecomp. speed = "
+ dfspeed.format(N * times * 1000.0
/ (idecomp)));
}
}
/**
* Main method
*
* @param args
* command-line arguments
*/
public static void main(String[] args) {
System.out.println("Testing packing and delta ");
testWithDeltas(false);
testWithDeltas(true);
System.out.println("Testing packing alone ");
test(false);
test(true);
}
}