Final QA (#562)

Author: gahjelle

functional-programming-python/function_scopes.py

@@ -6,6 +6,7 @@
 def outer():
     def inner():
         print("I am function inner()!")
+        return "return value from inner()"
 
     # Function outer() returns function inner().
     return inner

functional-programming-python/functions_as_arguments.py

@@ -19,4 +19,4 @@ def reverse_len(s):
 print(sorted(animals, key=reverse_len))
 
 # Using a lambda expression
-sorted(animals, key=lambda s: -len(s))
+print(sorted(animals, key=lambda s: -len(s)))

functional-programming-python/functions_overview.py

@@ -8,7 +8,7 @@ def func():
     print("I am function func()!")
 
 
-print(func())
+func()
 
 
 # Assign it to a new name.
@@ -20,9 +20,9 @@ def func():
 
 # Access a function object in a list.
 objects = ["cat", func, 42]
-objects[1]
+print(objects[1])
 
-print(objects[1]())
+objects[1]()
 
 # Use a function object as a key in a dictionary.
 # Note that this is probably not a good idea.

functional-programming-python/higher_order_reduce.py

@@ -3,44 +3,36 @@
 functional versions of `map()` and `filter()`.
 """
 
-# Compare `map()` to `custom_map()`.
-numbers = [1, 2, 3, 4, 5]
+from functools import reduce
 
-print(list(map(str, numbers)))
+numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
 
 
+# Compare `map()` to `custom_map()`.
 def custom_map(function, iterable):
-    from functools import reduce
-
     return reduce(
         lambda items, value: items + [function(value)],
         iterable,
         [],
     )
 
 
+print(list(map(str, numbers)))
 print(list(custom_map(str, numbers)))
 
 
 # Compare `filter()` to `custom_filter()`.
-numbers = list(range(10))
-
-
 def is_even(x):
     return x % 2 == 0
 
 
-print(list(filter(is_even, numbers)))
-
-
 def custom_filter(function, iterable):
-    from functools import reduce
-
     return reduce(
         lambda items, value: items + [value] if function(value) else items,
         iterable,
         [],
     )
 
 
+print(list(filter(is_even, numbers)))
 print(list(custom_filter(is_even, numbers)))

functional-programming-python/lambda_expressions.py

@@ -8,8 +8,7 @@ def reverse(s):
     return s[::-1]
 
 
-reverse("I am a string")
-
+print(reverse("I am a string"))
 
 reverse = lambda s: s[::-1]  # noqa E731
 print(reverse("I am a string"))

functional-programming-python/map_multiple.py

@@ -13,10 +13,10 @@ def add_three(a, b, c):
 print(
     list(
         map(
-            (lambda a, b, c: a + b + c),
-            [1, 2, 3],
-            [10, 20, 30],
-            [100, 200, 300],
+            lambda a, b, c: a + b + c,
+            [1, 2, 3, 4],
+            [10, 20, 30, 40],
+            [100, 200, 300, 400],
         )
     )
 )

functional-programming-python/map_single.py

@@ -17,19 +17,17 @@ def reverse(s):
 
 # Consume the iterator with a for loop.
 iterator = map(reverse, animals)
-for i in iterator:
-    print(i)
+for animal in iterator:
+    print(animal)
 
 # Consume the iterator with a call to `list()`.
 iterator = map(reverse, animals)
 print(list(iterator))
 
-
 # Use a lambda expression.
 iterator = map(lambda s: s[::-1], animals)
 print(list(iterator))
 
-
 # All the code in a single line.
 print(list(map(lambda s: s[::-1], ["cat", "dog", "hedgehog", "gecko"])))
 

functional-programming-python/reduce_with_initializer.py

@@ -17,4 +17,4 @@ def add_two_values(x, y):
 print(reduce(lambda x, y: x + y, [1, 2, 3, 4, 5], 100))
 
 # Use `sum()` and add a value instead.
-print(100 + sum([1, 2, 3, 4, 5]))
+print(sum([1, 2, 3, 4, 5], start=100))

functional-programming-python/reduce_with_two.py

@@ -25,8 +25,6 @@ def multiply(x, y):
 
 
 def factorial_with_reduce(n):
-    from functools import reduce
-
     return reduce(multiply, range(1, n + 1))
 
 
@@ -54,5 +52,5 @@ def greater(x, y):
 
 # Use lambda expressions to complete the tasks.
 print(reduce(lambda x, y: x + y, [1, 2, 3, 4, 5]))
-print(reduce(lambda x, y: x + y, ["foo", "bar", "baz", "quz"]))
+print(reduce(lambda x, y: x + y, ["cat", "dog", "hedgehog", "gecko"]))
 print(reduce((lambda x, y: x if x > y else y), [23, 49, 6, 32]))