Added task List Comprehension

Author: sofiiako

Data structures/Nested Lists/tests/test_task.py

@@ -10,6 +10,6 @@
 
 
 class TestCase(unittest.TestCase):
-    def test_loop(self):
+    def test_list(self):
         self.assertEqual('9', output[0], msg='The second printed element should be 9.')
         self.assertEqual('10', output[1], msg='The second printed element should be 10.')

Loops/List Comprehension/__init__.py

@@ -0,0 +1,14 @@
+type: edu
+files:
+- name: task.py
+  visible: true
+  placeholders:
+  - offset: 194
+    length: 35
+    placeholder_text: '''Use list comprehension to build the same list as above'''
+- name: tests/test_task.py
+  visible: false
+- name: __init__.py
+  visible: false
+- name: tests/__init__.py
+  visible: false

Loops/List Comprehension/task-info.yaml

@@ -0,0 +1,41 @@
+## List Comprehension
+
+You can use a loop to build a list (or another data structure).
+For example:
+
+```python
+my_list = []
+for i in range(5):
+    my_list.append(i)
+
+print(my_list)
+```
+Output:
+```text
+[0, 1, 2, 3, 4]
+```
+
+This is nice, but quite bulky. List comprehension offers a more compact syntax when you want to create a new list based on the values of an existing list
+or another iterable (tuple, string, array, range, etc). It does the same task and simplifies the program. Typically, list comprehensions are written in a single line of code.
+
+```python
+my_list = [i for i in range(5)]
+print(my_list)
+```
+Output:
+```text
+[0, 1, 2, 3, 4]
+```
+List comprehensions are also more efficient computationally than a for loop.
+
+In the code editor, use list comprehension to build `my_efficient_list` from the elements of `my_inefficient_list`
+by adding $10$ to each of them. For example, the first element of `my_inefficient_list` is $1 + 10 = 11$,
+so the first element of `my_efficient_list` should be $11 + 10 = 21$ and so on.
+
+
+<div class="hint">
+
+In the example above, we used `i for i in range(5)`. You can modify `i` as you like 
+right inside this expression. For example, to subtract `5` from every `i`, you can do 
+`i - 5 for i in range(5)`.
+</div>

Loops/List Comprehension/task.md

@@ -0,0 +1,11 @@
+starting_numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
+my_inefficient_list = []
+
+for i in starting_numbers:
+    my_inefficient_list.append(i + 10)
+
+print(my_inefficient_list)
+
+
+my_efficient_list = [i + 10 for i in my_inefficient_list]
+print(my_efficient_list)

Loops/List Comprehension/task.py

@@ -0,0 +1,11 @@
+import unittest
+
+from task import *
+
+
+# todo: replace this with an actual test
+class TestCase(unittest.TestCase):
+    def test_add(self):
+        test_list  = [i + 10 for i in my_inefficient_list]
+        self.assertEqual(test_list, my_efficient_list,
+                         msg="Each element of `my_efficient_list` should equal a corresponding element of `my_inefficient_list` plus 10.")

Loops/List Comprehension/tests/__init__.py

@@ -1,7 +1,9 @@
 content:
 - For loop
 - Loop over a string
+- List Comprehension
 - While loop
 - Break keyword
 - Else with loops
 - Continue keyword
+