Conditional Statements

Conditional statements allow a program to make decisions and execute different blocks of code depending on whether a condition is true or false. This is what gives your programs the ability to respond intelligently to different situations and data.

The if, elif, and else Statements

score = 78

if score >= 90:
    grade = "A"
elif score >= 75:
    grade = "B"
elif score >= 60:
    grade = "C"
else:
    grade = "D"

print(grade)   # Output: B

In the example above, Python checks each condition in order and executes the first block whose condition evaluates to true, skipping the rest.

Why This Matters in Data Science

• Filtering datasets based on specific criteria
• Flagging outliers or missing values during data cleaning
• Building rule-based logic before applying machine learning models

Next Up

Conditions decide what happens once. To repeat actions across data, you need loops, the focus of the next topic.