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package org.eclipse.jetty.util.statistic;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;
import org.junit.Test;
/* ------------------------------------------------------------ */
public class SampleStatisticTest
{
private static long[][] data =
{
{100,100,100,100,100,100,100,100,100,100},
{100,100,100,100,100,100,100,100,100,100,90,110},
{100,100,100,100,100,100,100,100,90,110,95,105,97,103},
{100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,100,90,110,95,105,97,103},
};
private static double[][] results =
{ /* {mean,stddev}*/
{100.0,0.0},
{100.0,Math.sqrt((10*10+10*10)/12.0)},
{100.0,Math.sqrt((10*10+10*10+5*5+5*5+3*3+3*3)/14.0)},
{100.0,Math.sqrt((10*10+10*10+5*5+5*5+3*3+3*3)/24.0)},
{100.0,Math.sqrt((10*10+10*10+5*5+5*5+3*3+3*3)/104.0)}
};
@Test
public void testData()
throws Exception
{
SampleStatistic stats = new SampleStatistic();
for (int d=0;d<data.length;d++)
{
stats.reset();
for (long x : data[d])
stats.set(x);
assertEquals("count"+d,data[d].length, (int)stats.getCount());
assertNearEnough("mean"+d,results[d][0], stats.getMean());
assertNearEnough("stddev"+d,results[d][1], stats.getStdDev());
}
}
private void assertNearEnough(String test,double expected, double actual)
{
double diff = Math.abs(expected-actual);
if (diff<0.1)
{
System.out.println("Near enough "+test+" diff="+diff);
return;
}
String failed = "Not near enough "+test+" expected="+expected+" actual="+actual+" diff="+diff;
System.err.println(failed);
assertTrue(failed,false);
}
}
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