Compound Logical Expressions

Sometimes you want to check more than one condition at a time. In Python, you can combine multiple conditions using logical operators:

• and: Both conditions must be true.
• or: At least one condition must be true.
• not: Inverts the condition.

1. Using and

age = 20
has_id = True

if age >= 18 and has_id:
    print("Allowed to enter")

• This prints "Allowed to enter" only if both conditions are true.

2. Using or

is_student = False
has_coupon = True

if is_student or has_coupon:
    print("Eligible for discount")

• This prints "Eligible for discount" if either is true.

3. Using not

logged_in = False

if not logged_in:
    print("Please log in")

• This prints "Please log in" because logged_in is false and not flips it.

4. Compound Conditions in Tables

Let's say we want to filter students who:

• Scored 70 or more

• AND their name starts with a letter before 'D'

students = [
    ["Name", "Score"],
    ["Alice", 85],
    ["Bob", 59],
    ["Charlie", 72],
    ["Diana", 91],
    ["Eve", 66]
]

filtered = [["Name", "Score"]]

for row in students[1:]:
    name = row[0]
    score = row[1]

    if score >= 70 and name[0] < 'D':
        filtered.append(row)

print(filtered)

Output

[['Name', 'Score'], ['Alice', 85'], ['Charlie', 72]]

Exercise: Try It Yourself!

Write a program that filters a list of books and selects only the ones that are:

• Priced above 30

• AND the genre is "Science"

  books = [
  ["Title", "Price", "Genre"],
  ["Deep Space", 45, "Science"],
  ["Cooking 101", 25, "Lifestyle"],
  ["The Quantum Code", 60, "Science"],
  ["Comfy Living", 35, "Home"]
  ]

  Expected Output

  [['Title', 'Price', 'Genre'], ['Deep Space', 45, 'Science'], ['The Quantum Code', 60, 'Science']]