New Random class for convenient random number generation.

1 files changed, 119 insertions, 0 deletions

diff --git a/test/randomtest.cc b/test/randomtest.cc
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+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/***************************************************************************
+ *            randomtest.cc
+ *
+ *  Sat Mar 26 08:48:53 CET 2016
+ *  Copyright 2016 André Nusser
+ *  andre.nusser@googlemail.com
+ ****************************************************************************/
+
+/*
+ *  This file is part of DrumGizmo.
+ *
+ *  DrumGizmo is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU Lesser General Public License as published by
+ *  the Free Software Foundation; either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  DrumGizmo is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public License
+ *  along with DrumGizmo; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
+ */
+#include <cppunit/extensions/HelperMacros.h>
+
+#include <random.h>
+
+#include <vector>
+#include <cmath>
+
+class RandomTest
+	: public CppUnit::TestFixture
+{
+	CPPUNIT_TEST_SUITE(RandomTest);
+	CPPUNIT_TEST(rangeTest);
+	CPPUNIT_TEST(normalTest);
+	CPPUNIT_TEST(chooseTest);
+	CPPUNIT_TEST_SUITE_END();
+
+public:
+	void setUp()
+	{
+	}
+
+	void tearDown()
+	{
+	
+	}
+
+	void rangeTest()
+	{
+		// check if random numbers are in the wanted range
+		Random rand;
+
+		float float_lb = -42.23;
+		float float_ub = 666.666;
+		int int_lb = -42;
+		int int_ub = 23;
+		for (int i = 0; i<10000; i++)
+		{
+			float rand_float = rand.floatInRange(float_lb, float_ub);
+			float rand_int = rand.intInRange(int_lb, int_ub);
+			CPPUNIT_ASSERT(rand_float >= float_lb && rand_float <= float_ub);
+			CPPUNIT_ASSERT(rand_int >= int_lb && rand_int <= int_ub);
+		}
+		
+		// check if the series of random numbers is the one we expect
+		// for a certain seed.
+		rand = Random(666);
+		CPPUNIT_ASSERT_EQUAL(0, rand.intInRange(0,100));
+		CPPUNIT_ASSERT_EQUAL(61, rand.intInRange(0,100));
+		CPPUNIT_ASSERT_EQUAL(23, rand.intInRange(0,100));
+	}
+
+	void normalTest()
+	{
+		// This test might theoretically fail but it is extremely unlikely to happen.
+		Random rand;
+
+		float real_mean = 42.0;
+		float real_stddev = 2.0;
+		int nr_of_samples = 50000;
+
+		float sum = 0.;
+		float sum_of_squares = 0.;
+		for (int i=0; i<nr_of_samples; i++)
+		{
+			float rand_float = rand.normalDistribution(real_mean, real_stddev);
+			sum += rand_float;
+			sum_of_squares += rand_float*rand_float;
+		}
+
+		float estimated_mean = sum/nr_of_samples;
+		float estimated_stddev = sqrt(sum_of_squares/nr_of_samples - estimated_mean*estimated_mean);
+
+		float epsilon = 0.1;
+		CPPUNIT_ASSERT(estimated_mean >= real_mean-epsilon && estimated_mean <= real_mean+epsilon);
+		CPPUNIT_ASSERT(estimated_stddev >= real_stddev-epsilon && estimated_stddev <= real_stddev+epsilon);
+	}
+
+	void chooseTest()
+	{
+		Random rand;
+
+		std::vector<int> vec = { 42, 42, 42 };
+		int nr_of_samples = 1000;
+
+		for (int i=0; i<nr_of_samples; i++)
+		{
+			CPPUNIT_ASSERT_EQUAL(42, rand.choose(vec));
+		}
+	}
+};
+
+// Registers the fixture into the 'registry'
+CPPUNIT_TEST_SUITE_REGISTRATION(RandomTest);