Closes #66

This commit should make Travis fail the build (On purpose making it
fail to see if it spots when a test fails). Before, it was not failing
even though a test was failing.

.gitignore

@@ -10,6 +10,7 @@ ands/algorithms/greedy/huffman.py
 ands/algorithms/graphs/
 /ands/algorithms/math/combinatorics/
 /ands/algorithms/math/
+/ands/algorithms/cg/
 
 *.eggx
 *.py[cod]

.travis.yml

@@ -8,22 +8,9 @@ python:
   - 3.5
   - 3.6
 
-# command to install dependencies
 install:
-  #- pip install matplotlib
   - pip install coveralls
   - pip install -e .
 
-# For plots when testing.
-# See: https://stackoverflow.com/a/35403128/3924118
-#before_script: # configure a headless display to test plot generation
-#- "export DISPLAY=:99.0"
-#- "sh -e /etc/init.d/xvfb start"
-#- sleep 3 # give xvfb some time to start
-
-# command to run tests
 script: scripts/travis.sh
 
-after_success:
-  - coveralls
-

ands/algorithms/README.md

@@ -16,7 +16,9 @@ A few interesting algorithms which may be implemented in the future.
 
 ## Geometry
 
-- [Line segment intersection](https://en.wikipedia.org/wiki/Line_segment_intersection)
+### [Line-Segment Intersection](https://en.wikipedia.org/wiki/Line_segment_intersection)
+
+- [Bentley–Ottmann algorithm](https://en.wikipedia.org/wiki/Bentley%E2%80%93Ottmann_algorithm)
 
 ### Convex Hull
 

ands/algorithms/numerical/gradient_descent.py

@@ -27,7 +27,7 @@
 def gradient_descent(x0: float,
                      df: callable,
                      step_size: float = 0.01,
-                     max_iter: int = 50,
+                     max_iter: int = 100,
                      tol: float = 1e-6):
     """Finds a local minimum of a function whose derivative is df starting from
     an initial guess x0 using a step size = step_size."""
@@ -36,8 +36,8 @@ def gradient_descent(x0: float,
 
     x = x0
 
-    for _ in range(max_iter):
-        x_next = x + -step_size * df(x)  # Gradient descent step.
+    for i in range(max_iter):
+        x_next = x - step_size * df(x)  # Gradient descent step.
 
         if abs(x_next - x) < tol * abs(x_next):
             x = x_next

ands/ds/LinearProbingHashTable.py

@@ -8,7 +8,7 @@
 
 Created: 01/06/2015
 
-Updated: 28/09/2017
+Updated: 02/04/2018
 
 # Description
 
@@ -55,9 +55,9 @@
 # References
 
 - http://interactivepython.org/runestone/static/pythonds/SortSearch/Hashing.html
-- http://stackoverflow.com/questions/279539/best-way-to-remove-an-entry-from-a-hash-table
-- http://stackoverflow.com/questions/9835762/find-and-list-duplicates-in-a-list
-- http://stackoverflow.com/questions/1541797/check-for-duplicates-in-a-flat-list
+- https://stackoverflow.com/q/279539/3924118
+- https://stackoverflow.com/q/9835762/3924118
+- https://stackoverflow.com/q/1541797/3924118
 - https://en.wikipedia.org/wiki/Associative_array
 - https://en.wikipedia.org/wiki/Hash_table
 - https://en.wikipedia.org/wiki/Hash_function
@@ -137,6 +137,8 @@ def put(self, key: object, value: object) -> None:
 
         if key is None:
             raise TypeError("key cannot be None.")
+        if not isinstance(key, Hashable):
+            raise TypeError("key must be an instance of a hashable type")
 
         self._put(key, value, self._n)
 
@@ -213,6 +215,9 @@ def get(self, key: object) -> object:
 
         if key is None:
             raise TypeError("key cannot be None.")
+        if not isinstance(key, Hashable):
+            raise TypeError("key must be an instance of a hashable type")
+
         value = LinearProbingHashTable._get(key, self._keys, self._values,
                                             self._n)
 

ands/ds/README.md

@@ -19,7 +19,8 @@ A few interesting data structures which may be implemented in the future.
 
 ### Lists
 
-- Skip list
+- [Skip list](https://brilliant.org/wiki/skip-lists/)
+- [Doubly connected edge list](https://en.wikipedia.org/wiki/Doubly_connected_edge_list)
 
 ## Trees
 

scripts/run_tests.sh

@@ -111,7 +111,7 @@ then
 
         switch_to_virtual_environment
 
-        install_dependencies_in_virtual_environment coveralls pdoc "-e ."
+        install_dependencies_in_virtual_environment coveralls "-e ."
 
         # If we have 3 parameters, then probably the user wants to execute a specific test.
         if [ "$#" =  "3" ]

scripts/travis.sh

@@ -6,3 +6,4 @@ cd tests/
 coverage run -m unittest discover . -v
 mv .coverage ../.coverage
 cd ../
+coveralls

tests/algorithms/numerical/test_gradient_descent.py

@@ -36,4 +36,4 @@ def test_type_error_when_df_not_callable(self):
         self.assertRaises(TypeError, gradient_descent, 0.3, 5)
 
     def test_find_local_min_of_f(self):
-        self.assertAlmostEqual(gradient_descent(6, df), 9 / 4, 5)
+        self.assertAlmostEqual(gradient_descent(3, df), 9 / 4, 5)

tests/ds/test_LinearProbingHashTable.py

@@ -17,7 +17,7 @@
 
 # Reference
 
-- http://stackoverflow.com/questions/9755538/how-do-i-create-a-list-of-unique-random-numbers
+- https://stackoverflow.com/q/9755538/3924118
 
 """
 
@@ -92,6 +92,13 @@ def test_get_key_None(self):
         t = LinearProbingHashTable()
         self.assertRaises(TypeError, t.get, None)
 
+    def test_get_non_hashable_type(self):
+        t = LinearProbingHashTable()
+        t.put(23, 31)
+        t.put(11, 13)
+        self.assertRaises(TypeError, t.get, [])
+        self.assertRaises(TypeError, t.get, {})
+
     def test_get_empty_table(self):
         t = LinearProbingHashTable()
         self.assertIsNone(t.get(3))
@@ -107,13 +114,6 @@ def test_get_no_key_found(self):
         t["four"] = 4
         self.assertIsNone(t.get("five"))
 
-    def test_get_non_hashable_type(self):
-        t = LinearProbingHashTable()
-        t.put(23, 31)
-        t.put(11, 13)
-        self.assertRaises(TypeError, t.get, [])
-        self.assertRaises(TypeError, t.get, {})
-
     def test_get_all(self):
         t = LinearProbingHashTable()
 
@@ -129,6 +129,11 @@ def test_put_key_None(self):
         t = LinearProbingHashTable()
         self.assertRaises(TypeError, t.put, None, 5)
 
+    def test_put_non_hashable_type(self):
+        t = LinearProbingHashTable()
+        self.assertRaises(TypeError, t.put, [], 12)
+        self.assertRaises(TypeError, t.put, {}, None)
+
     def test_put_key_not_None_value_None(self):
         t = LinearProbingHashTable()
         t.put(3, None)
@@ -141,11 +146,6 @@ def test_put_key_not_None_value_not_None(self):
         self.assertTrue(t.size, 1)
         self.assertEqual(t.get(5), 19)
 
-    def test_put_non_hashable_type(self):
-        t = LinearProbingHashTable()
-        self.assertRaises(TypeError, t.put, [], 12)
-        self.assertRaises(TypeError, t.put, {}, None)
-
     def test_put_same_key_multiple_times(self):
         t = LinearProbingHashTable()
         t.put(3, "three")
@@ -189,6 +189,11 @@ def test_delete_key_None(self):
         t = LinearProbingHashTable()
         self.assertRaises(TypeError, t.delete, None)
 
+    def test_delete_non_hashable_type(self):
+        t = LinearProbingHashTable()
+        self.assertRaises(TypeError, t.delete, [])
+        self.assertRaises(TypeError, t.delete, {})
+
     def test_delete_empty_table(self):
         t = LinearProbingHashTable()
         self.assertIsNone(t.delete(3))
@@ -198,11 +203,6 @@ def test_delete_key_not_present(self):
         t.put(-10, "testing deletion when key not in the table")
         self.assertIsNone(t.delete(7))
 
-    def test_delete_non_hashable_type(self):
-        t = LinearProbingHashTable()
-        self.assertRaises(TypeError, t.delete, [])
-        self.assertRaises(TypeError, t.delete, {})
-
     def test_delete_some(self):
         t = LinearProbingHashTable()
         ls = [(1, 3), (5, "two"), (2.72, 10), ("one", 3.14), (1, "seven")]