Create find_maxima function

hands_on/local_maxima_part2/local_maxima.py

@@ -1,10 +1,33 @@
-def find_maxima(x):
-    """Find local maxima of x.
+def find_maxima(points):
+    """Find local maxima of points.
 
     Input arguments:
-    x -- 1D list of real numbers
+    points -- 1D list of real numbers
 
     Output:
-    idx -- list of indices of the local maxima in x
+    indices -- list of indices of the local maxima in points
     """
-    return []
+    indices = []
+    plateau_idx = []
+
+    if not points:
+        print("No input given")
+        return []
+    elif len(points) == 1:
+        return [0]
+
+    if points[0] > points[1]:
+        indices.append(0)
+    for i in range(1, len(points)-1):
+        if points[i] > points[i+1] and points[i] > points[i-1]:
+            indices.append(i)
+            plateau_idx = []
+        if points[i] == points[i+1]:
+            plateau_idx.append(i)
+        if points[i] > points[i+1] and plateau_idx:
+            indices.append(plateau_idx[0])
+            plateau_idx = []
+
+    if points[-1] > points[-2]:
+        indices.append(len(points)-1)
+    return indices

hands_on/local_maxima_part2/test_local_maxima.py

@@ -23,8 +23,14 @@ def test_find_maxima_empty():
 
 
 def test_find_maxima_plateau():
-    raise Exception('not yet implemented')
+    values = [1, 2, 2, 1]
+    expected = [1]
+    maxima = find_maxima(values)
+    assert maxima == expected
 
 
 def test_find_maxima_not_a_plateau():
-    raise Exception('not yet implemented')
+    values = [1, 2, 2, 3, 1]
+    expected = [3]
+    maxima = find_maxima(values)
+    assert maxima == expected

local_maxima.py

@@ -0,0 +1,17 @@
+def find_maxima(points):
+    indices = []
+
+    if not points:
+        print("No input given")
+        return []
+    elif len(points) == 1:
+        return [0]
+
+    if points[0] > points[1]:
+        indices.append(0)
+    for i in range(1, len(points)-1):
+        if points[i] > points[i+1] and points[i] > points[i-1]:
+            indices.append(i)
+    if points[-1] > points[-2]:
+        indices.append(len(points)-1)
+    return indices