Testing Class Material

hands_on/local_maxima_part3_debug/local_maxima.py

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+def find_maxima(x):
+    """Find local maxima of x.
+
+    Input arguments:
+    x -- 1D list of real numbers
+
+    Output:
+    idx -- list of indices of the local maxima in x
+    """
+
+    maxima = []
+
+    len_x = len(x)
+    if len_x == 0:
+        return maxima
+
+    maxima = check_first_element(x, maxima)
+    maxima = check_last_element(x, maxima)
+
+    # Check numbers in between
+    i = 1
+    while i < len_x - 1:
+        if x[i] > x[i - 1]:
+            # We have found a potential maximum or start of a plateau
+            plateau_start = i
+            while i < len_x - 1 and x[i] == x[i + 1]:
+                i += 1
+            plateau_end = i
+            if x[plateau_end] > x[plateau_end + 1]:
+                maxima.append(plateau_start)
+        i += 1
+    return maxima
+
+
+def check_first_element(x, maxima):
+    if x[0] > x[1]:
+        maxima.append(0)
+    return maxima
+
+
+def check_last_element(x, maxima):
+    if x[-1] > x[-2]:
+        maxima.append(len(x) - 1)
+    return maxima
+
+
+if __name__ == "__main__":
+    result = find_maxima([1, 2, 2, 1])
+    print(result)

hands_on/local_maxima_part3_debug/test_local_maxima.py

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+import numpy as np
+import pytest
+
+from local_maxima import find_maxima
+
+
+def test_find_maxima():
+    values = [1, 3, -2, 0, 2, 1]
+    expected = [1, 4]
+    maxima = find_maxima(values)
+    assert maxima == expected
+
+
+def test_find_maxima_edges():
+    values = [4, 2, 1, 0, 1, 5]
+    expected = [0, 5]
+    maxima = find_maxima(values)
+    assert maxima == expected
+
+
+def test_find_maxima_empty():
+    values = []
+    expected = []
+    maxima = find_maxima(values)
+    assert maxima == expected
+
+
+def test_find_maxima_plateau():
+    values = [1, 2, 2, 1]
+    expected = [1]
+    maxima = find_maxima(values)
+    assert maxima == expected
+
+
+def test_find_maxima_not_a_plateau():
+    values = [1, 2, 2, 3, 1]
+    expected = [3]
+    maxima = find_maxima(values)
+    assert maxima == expected
+
+
+# the tests below here fail, can you get them to pass?
+
+
+def test_find_maxima_correct_order():
+    # TASK: get this test to pass
+    values = [2, 1, 5, 1, 9]
+    expected = [0, 2, 4]
+    maxima = find_maxima(values)
+    assert maxima == expected
+
+
+def test_find_maxima_one_value():
+    # TASK: get this test to pass
+    values = [1]
+    expected = [0]
+    maxima = find_maxima(values)
+    assert maxima == expected
+
+
+def test_find_maxima_long_plateau():
+    # TASK: Change the implementation for when there is a plateau
+    # for uneven plateau length, return the middle index, e.g. [1, 2, *2*, 2, 1] --> [2]
+    # for even plateau length, return the index left of the middle  e.g. [1, 2, *2*, 2, 2, 1] --> [2]
+    values = [1, 2, 2, 2, 2, 2, 1, 8, 0]
+    expected = [3, 7]
+    maxima = find_maxima(values)
+    assert maxima == expected
+
+
+def test_find_maxima_plateau_at_end():
+    # TASK: make sure plateaus at the end are handled properly (see test above)
+    values = [1, 2, 2]
+    expected = [1]
+    maxima = find_maxima(values)
+    assert maxima == expected
+
+
+def test_find_maxima_plateau_at_start():
+    # TASK: make sure plateaus at the start are handled properly (see test above)
+    values = [1, 1, 0, 0]
+    expected = [0]
+    maxima = find_maxima(values)
+    assert maxima == expected
+
+
+def test_find_maxima_all_same_values():
+    # TASK: implement a check for lists where there is no local maximum
+    values = [1, 1]
+    expected = [0]
+    maxima = find_maxima(values)
+    assert maxima == expected
+
+
+def test_find_maxima_letters():
+    # stings can be evaluated with > and <, who knew!
+    # Find an easy solution so that both "t"s are recognised as local maxima
+    values = ["T", "e", "s", "t", "s", "!"]
+    expected = [0, 3]
+    maxima = find_maxima(values)
+    assert maxima == expected
+
+
+def test_find_maxima_new_inputs_to_make_current_function_fail():
+    # should you actually be done with all tests, then you can think of other cases where the current function fails
+    # and write tests for them and fix them
+    assert False