def test_averageMessageLengths(self):
for i in range(10):
weights = [random.randrange(2*20) for x in range(1000)]
for D in range(2, 15):
huff_codes = huffman(weights, D)
gdm_codes = GDM(weights, D)
huff_avg = averageMessageLength(weights, huff_codes)
gdm_avg = averageMessageLength(weights, gdm_codes)
self.assertEqual(huff_avg, gdm_avg)
def test_paperExample(self):
elements = [
0.20, 0.18, 0.10, 0.10, 0.10, 0.06, 0.06, 0.04, 0.04, 0.04, 0.04,
0.03, 0.01
]
result = huffman(elements, 2)
elements.sort()
result.sort(reverse=True)
avgLength = 0
for i in range(len(elements)):
avgLength += result[i] * elements[i]
expected = 3.42
self.assertAlmostEqual(
avgLength, expected) #test by optimal average message length
def test_paperExample(self):
elements = [0.22, 0.20, 0.18, 0.15, 0.10, 0.08, 0.05, 0.02]
result = compressByRunLengths(huffman(elements, 4))
expected = [(3, 2), (2, 3), (1, 3)]
self.assertEqual(result, expected)
def test_fourTernary(self):
elements = [4, 3, 6, 8]
result = compressByRunLengths(huffman(elements, 3))
expected = [(2, 2), (1, 2)]
self.assertEqual(result, expected)
def test_sameWeigths(self):
for d in range(2, 15):
elements = [1] * d
result = compressByRunLengths(huffman(elements, d))
expected = [(1, d)]
self.assertEqual(result, expected)
def test_empty(self):
elements = []
expected = []
for d in xrange(2, 12):
result = (huffman(elements, d))
self.assertEqual(result, expected)
def test_fourElements(self):
elements = [4, 3, 6, 8]
result = compressByRunLengths(huffman(elements, 2))
expected = [(3, 2), (2, 1), (1, 1)]
self.assertEqual(result, expected)
def test_twoElements(self):
elements = [4, 2]
result = compressByRunLengths(huffman(elements, 2))
expected = [(1, 2)]
self.assertEqual(result, expected)
def test_lowOutputAlphabet(self):
with self.assertRaises(Exception) as context:
huffman([], 1)
def test_unusualWeights(self):
elements = [-4, 0, 18.3, 9]
result = compressByRunLengths(huffman(elements, 2))
expected = [(3, 2), (2, 1), (1, 1)]
self.assertEqual(result, expected)
def test_oneElement(self):
elements = [4]
expected = [0]
for d in xrange(2, 10):
result = (huffman(elements, d))
self.assertEqual(result, expected)