public void CostaSoaresTest()
{
// Exact same order should produce 1.0
Statistics stat1 = new Statistics(new[] { 1.0, 2, 3, 4 });
Statistics stat2 = new Statistics(new[] { 1.0, 2, 3, 4 });
Assert.AreEqual(1.0, stat1.CostaSoares(stat2));
// Same order but differing intensities should also produce 1.0,
// since this is a rank correlation
stat2 = new Statistics(new[] { 5.0, 6, 7, 8 });
Assert.AreEqual(1.0, stat1.CostaSoares(stat2));
// Flipping the order of larger numbers should yeild a lower score
// than flipping smaller numbers
stat2 = new Statistics(new[] { 1.0, 2, 4, 3 });
double cs1 = stat1.CostaSoares(stat2);
stat2 = new Statistics(new[] { 2.0, 1, 3, 4 });
double cs2 = stat1.CostaSoares(stat2);
Assert.IsTrue(cs1 < cs2);
// Swapping highest rank with lowest should be even worse
stat2 = new Statistics(new[] { 4.0, 2, 3, 1 });
Assert.IsTrue(stat1.CostaSoares(stat2) < cs1);
// Two same ranked should have less impact than flipping
stat2 = new Statistics(new[] { 1.0, 1, 3, 4 });
double cs3 = stat1.CostaSoares(stat2);
Assert.IsTrue(cs2 <= cs3);
// Well, actually it appears to yield 1.0, which seems broken
// Assert.AreEqual(1.0, cs3);
// Try the same thing with 1 and 2 rankings
stat2 = new Statistics(new[] { 1.0, 2, 3, 3.0 });
cs3 = stat1.CostaSoares(stat2);
Assert.IsTrue(cs1 <= cs3);
// Again this yields 1.0, which seems more broken
// Assert.AreEqual(1.0, cs3);
// Try everything equal
// stat2 = new Statistics(new[] { 1.0, 1, 1, 1 });
// cs3 = stat1.CostaSoares(stat2);
// Wow! 1.0 again. Now that seems really broken
// Assert.AreEqual(1.0, cs3);
// Reversing the order should yield -1
stat2 = new Statistics(new[] { 4.0, 3, 2, 1 });
Assert.AreEqual(-1.0, stat1.CostaSoares(stat2));
// Reordering smaller numbers below the top 4 should have no impact
stat1 = new Statistics(new[] { 1.0, 2, 3, 4, 5, 6, 7, 8 });
stat2 = new Statistics(new[] { 2.0, 1, 4, 3, 5, 6, 7, 8 });
cs3 = stat1.CostaSoares(stat2, 4);
Assert.AreEqual(1.0, cs3);
cs3 = stat1.CostaSoares(stat2);
Assert.IsTrue(cs3 > 0.95);
// All same intensity of lower ranked numbers should also have no impact
stat2 = new Statistics(new[] { 0.0, 0, 0, 0, 5, 6, 7, 8 });
cs3 = stat1.CostaSoares(stat2, 4);
Assert.AreEqual(1.0, cs3);
// And some similar tests of negative correlation
stat2 = new Statistics(new[] { 8.0, 7, 6, 5, 0, 0, 0, 0 });
cs3 = stat1.CostaSoares(stat2, 4);
Assert.AreEqual(-1.0, cs3);
stat2 = new Statistics(new[] { 8.0, 7, 6, 5, 4, 3, 0, 0 });
cs3 = stat1.CostaSoares(stat2, 4);
Assert.AreEqual(-1.0, cs3);
stat2 = new Statistics(new[] { 8.0, 7, 6, 5, 4, 3, 2, 1 });
cs3 = stat1.CostaSoares(stat2);
Assert.AreEqual(-1.0, cs3);
// And perhaps the most broken thing of all, just having the most
// intense peak in the right place for a set of 8 gives you 1.0
// But this works with more recent fixes.
stat2 = new Statistics(new[] { 0.0, 0, 0, 0, 0, 0, 0, 8 });
cs3 = stat1.CostaSoares(stat2);
Assert.IsTrue(cs3 < 0);
// But swapping highest and lowest should still be worse than
// swapping second highest and second lowest.
stat2 = new Statistics(new[] { 8.0, 2, 3, 4, 5, 6, 7, 1 });
cs1 = stat1.CostaSoares(stat2);
stat2 = new Statistics(new[] { 1.0, 7.0, 3, 4, 5, 6, 2, 8 });
cs2 = stat1.CostaSoares(stat2);
Assert.IsTrue(cs1 < cs2);
}
