Day 9 of 50 Days of Python: Sets, Strings, & Ranges

Part of Week 2: Data Structures

So, we are nearly 1/5 of the way through this Python series! Today, we’re going to focus on sets, strings and ranges. These are very versatile tools that play a big role in problem-solving and managing data efficiently.

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Sets: Unique and Unordered Collections

A set is a collection of unique and unordered elements. Unlike lists or tuples, sets automatically discard duplicate values and they don’t preserve the order of elements.

Key Features of Sets

• Unique Elements: Duplicates are automatically removed.

• Unordered: There’s no concept of indexing.

• Mutable: You can add/remove items, like lists and dictionaries.

Creating sets:

# Set of unique integers
numbers = {1, 2, 3, 4, 4, 5}
print(numbers) # Output: {1, 2, 3, 4, 5}

# Empty set
empty = {}

# Creating a set from a list
set_from_list = set([1, 2, 3])

• Adding and removing items:

  numbers.add(6)      # Adds 6 
  numbers.remove(3)   # Removes 3 (Errors if 3 doesn't exists) 
  numbers.discard(10) # Removes 10 (However, no error if 10 doesn't exist)

• Set operations:

  evens = {2, 4, 6} 
  odds = {1, 3, 5} 
  print(numbers.union(evens))        # Combines sets
  print(numbers.intersection(odds))  # Common elements
  print(numbers.difference(odds))    # Elements in numbers not in odds

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Strings: Sequence of Characters

A string is a sequence of characters enclosed in quotes. Strings are essential for handling text data in Python

Key Properties of Strings

• Immutable: You can’t modify a string “directly”.

• Ordered: You can access characters by index.

Creating strings:

name = "Python"
sentence = 'This is also a string.'
mutli_line = """ This is string notation that can span
mutiple lines in your code."""

• Accessing characters:

  print(name[0]) # P 
  print(name[-1] # n

• Slicing strings:

  print(name[0:3] # Pyt 
  print(name[::2] # Pto (Every second character)

• Methods to manipulate strings:

  print(name.lower())          # python 
  print(name.upper())          # PYTHON 
  print(name.replace("P", "J") # Replace P with J

• Checking substrings:

  print("Py" in name) # Checks if Py is in name, outputs: True

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Ranges: Generating Sequences of Numbers

The range() function generates a sequence of numbers. While it’s normally used in loops, ranges are also useful for managing ordered, numerical data.

Creating ranges:

r1 = range(5) # 0 to 4 
r2 = range(1, 10, 2) # 1 to 9, steps of 2

• Iterating through a range:

  for i in range(1, 6): 
      print(i) # Outputs: 1,2,3,4,5

• Convert to a list:

  numbers = list(range(3, 9)) 
  print(numbers)

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Use Cases for Data Engineers

• Sets: Great for identifying unique values or performing operations like union or interaction on datasets

• Strings: Used for parsing, cleaing and transforming raw text data. As well as setting configurations like environment → env = “Prod”.

• Ranges: Often helpful when creating test datasets or lopping over numerical sequences.

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Hands on Exercises

1. Create a set of numbers from 1 to 5, add the number 6, and remove 3.

2. Assign a sentence to a variable called sentence, convert it to uppercase, remove all spaces and check if a word is in your sentence.

3. Create a list of even numbers from 2 to 20 using range().

Any issues let me know in the comments or drop what you did within a comment so I can see how you’re all progressing!

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Next Up: Day 10 - List Comprehensions

Tomorrow we’ll explore list and dictionary comprehensions to quick and efficiently create and manipulate data structures!

Keep practicing what you’ve learnt in the meantime, and remember…. Happy coding!