feat: add list comprehension tutorial (#131)

* add list comprehension tutorial

* Update README.md

Co-authored-by: Sarah Abderemane <[email protected]>

* Update lists/comprehension.py

Co-authored-by: Sarah Abderemane <[email protected]>

* Update lists/comprehension.py

Co-authored-by: Sarah Abderemane <[email protected]>

* Update lists/comprehension.py

Co-authored-by: Sarah Abderemane <[email protected]>

* Update lists/comprehension.py

Co-authored-by: Sarah Abderemane <[email protected]>

* fix challenge steps

* rename file for consistency

* fix trailing space

Co-authored-by: Sarah Abderemane <[email protected]>

README.md

@@ -38,6 +38,7 @@ Each file contains:
 |How to alter a list                        | [alterning-lists.py](lists/altering-lists.py)                  | 
 |How to declare a list                      | [declaring-lists.py](lists/declaring-lists.py)                 | 
 |How to index a list                        | [indexing-lists.py](lists/indexing-lists.py)                   | 
+|List comprehension                              | [list-comprehension.py](lists/list-comprehension.py)                |
 | **Conditions**                            | 
 |How to make conditions                     | [if-else.py](conditions/if-else.py)                            |
 | **Loops**                                 | 

lists/list-comprehension.py

@@ -0,0 +1,53 @@
+# ------------------------------------------------------------------------------------
+# Tutorial: List comprehension
+# ------------------------------------------------------------------------------------
+# It's a Python feature to iterate and create a list from some other list in a
+# shorter and declarative way than loops.
+
+
+# In general there is a very common for loop structure that looks like this:
+for_loop_squares = []
+
+for i in range(10):
+    for_loop_squares.append(i * i)
+
+print(for_loop_squares)  # [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
+
+
+# With list comprehension you can do the exact same thing in one line.
+# the syntax is:
+# new_list = [expression for member in iterable]
+comprehension_squares = [x * x for x in range(10)]
+
+print(comprehension_squares)  # [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
+
+
+# You can even add conditionals to the list comprehension, the condition is place at the end of the list comprehension, just like that:
+# new_list = [expression for member in iterable if condition]
+comprehension_even_squares_numbers = [x * x for x in range(10) if x % 2 == 0]
+
+print(comprehension_even_squares_numbers)  # [0, 4, 16, 36, 64]
+
+
+# But if you can do if/else logic, you need to place the condition before the for loop just like that:
+comprehension_even_squares_numbers_and_odd_numbers_is_zero = [x * x if x % 2 == 0 else 0 for x in range(10)]
+
+print(comprehension_even_squares_numbers_and_odd_numbers_is_zero)  # [0, 0, 4, 0, 16, 0, 36, 0, 64, 0]
+
+
+# We can summarize the 3 formats of list comprehension. The basic format of a list comprehension is like:
+# new_list = [expression for member in iterable]
+
+# With only one condition
+# new_list = [expression for member in iterable if condition]
+
+# With if/else logic:
+# new_list = [expression if condition else other_expression for x in sequence]
+
+
+# ------------------------------------------------------------------------------------
+# Challenge: FIZZBUZZ
+# Create a list comprehesion that returns the numbers from 0 to 100 but:
+#   1 -. if the number is divisible by 3 and 5, append to the list the word "FizzBuzz"
+#   2 -. else, append to the list the number
+# ------------------------------------------------------------------------------------