Python Data Structures 🏗️

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✅ Objectives

  • Review the Sequence types: list, tuple, range (and str)
    • Lists: understand CRUD operations with list values
    • Tuples:
      • Discuss: mutable vs immutable
      • Create and access values in tuples
  • Ranges: and how they’re useful in loops
  • Learn about Set types (time permitting)
  • Dictionaries:
    • a mapping data structure
    • know all CRUD operations
  • Loops: create for and while loops with sequences
  • Use list comprehensions to emulate JS map, filter and find functions

List... array's Pythonic twin?

  • ordered collection of elements
  • aka sequence
  • mutable
  
  my_list = ["hello", "world", 42, ["another", "list"]]
Let's dive into the code! 🌊

Tuples–when values are forever 💎

  • ordered collection of values
  • aka sequence
  • immutable
  
    my_tuple = (4, 2, "Miyuki", True)
  

  
    for num in range(8):
      print(f"The count is {num}")

Dictionaries 📖 Python's JSON

Creating dictionaries:
  
    cat_1 = {
      'name': 'Simon',
      'color': 'ginger',
      'age': 10
    }
  
  
    cat_2 = dict(name='Miyuki', color='grey', age=10)
Reading and adding values 👓
cat_1 = {
      'name': 'Simon',
      'color': 'ginger',
      'age': 10
}
cat_1['color']
# => ginger
cat_1.get('age')
# => 10
cat_1.get('mood')
# => None
cat_1['mood'] = 'hungry'
cat_1.setdefault('breed', 'Munchkin')
Let's try it! 🚀
Updating and Deleting values 📝 ❌
cat_1 = {
      'name': 'Simon',
      'color': 'ginger',
      'age': 10,
      'mood': 'hungry'
}
cat_1['mood'] = 'sleepy'
cat_1.update(age=11, mood='feisty')
print(cat_1)
# {'name': 'Simon', 'color': 'ginger', 'age': 11, 'mood': 'feisty'}
del cat_1('age')
cat_1.pop('mood')
print(cat_1)
# {'name': 'Simon', 'color': 'ginger'}
Let's do it! 🛠️
For loops: let me reiterate 🐈🐈🐈

break keyword 🔑

In a loop, the break keyword escapes the loop, regardless of the iteration number. Once break executes, the program will continue to execute after the loop. 
numbers = [0, 254, 2, -1, 3]

for num in numbers:
  if (num < 0):
    print("Negative number detected!")
    break
  print(num)
  
# 0
# 254
# 2
# Negative number detected!

continue keyword 🔑

In Python, a while loop will repeatedly execute a code block as long as a condition evaluates to True. 
big_number_list = [1, 2, -1, 4, -5, 5, 2, -9]

# Print only positive numbers:
for i in big_number_list:
  if i < 0:
    continue
  print(i)

while loops 🔍

In Python, the continue keyword is used inside a loop to skip the remaining code inside the loop code block and begin the next loop iteration. 
hunger = 5
while hunger > 0:
  print('munch!')
  hunger -= 1 # be sure to progress your condition towards the base case!
# this will print 'munch!' 5 times

List Comprehension 💡

List comprehension is a simpler method to create a list from an existing list. It is generally a list of iterables generated with an option to include only the items which satisfy a condition.