If else statement in Python
අන්තිමට model එකකට decision එකක් ගන්න වෙනවා — "probability 0.5ට වැඩිනම්, yes කියලා predict කරන්න." ඒ decision එකේ core එකේ තියෙන්නෙ if/else statement එකක්.
Every model eventually makes a decision — "if probability > 0.5, predict yes." That decision, at its core, is an if/else statement.
Lesson 6 of 64 · Part 1 · Python & Data Basics · Python Fundamentals · bilingual notes (English + සිංහල)
Why this matters. Every model eventually makes a decision — "if probability > 0.5, predict yes." That decision, at its core, is an if/else statement.
සිංහලෙන්: අන්තිමට model එකකට decision එකක් ගන්න වෙනවා — "probability 0.5ට වැඩිනම්, yes කියලා predict කරන්න." ඒ decision එකේ core එකේ තියෙන්නෙ if/else statement එකක්.
What you'll use this for. You'll use this to clean messy data ("if value is missing, fill it with the average") before you ever train a model.
සිංහලෙන්: Model එකක් train කරන්නත් කලින්, අපිරිසිදු data clean කරන්න මේක පාවිච්චි කරනවා ("value එක නැත්නම්, average එකෙන් පුරවන්න").
Key principles
- Only one branch ever runs. Python checks conditions top to bottom and stops at the first True — later
elifblocks are simply skipped.
එකම ශාඛාවක් විතරයි කවදාවත් run වෙන්නෙ
Walkthrough
simple if else statement
a = 30
b = 50
if (a>b):
print('a is the greatest number')
else:
print('b is the greatest number')Output
b is the greatest numbera = int(input('Enter the first number : '))
b = int(input('Enter the second number : '))
if (a>b):
print('First number is the greatest')
else:
print('Second number is the greatest')Output
Enter the first number : 16
Enter the second number : 20
Second number is the greatestif elif else statement
a = 15
b = 25
c = 30
if (b<a>c):
print('a is the greatest number')
elif (a<b>c):
print('b is the greatest number')
else:
print('c is the greatest number')Output
c is the greatest numbernested if statement
a = 20
b = 40
c = 60
if (a>b):
if (a>c):
print('a is the greatest number')
else:
print('c is the greatest number')
else:
if (b>c):
print('b is the greatest number')
else:
print('c is the greatest number')Output
c is the greatest numberKeep going: ← Lesson 5 · Lesson 7 → · Track it in the Self Guide
Finished this one?
Part of Self Guide · Stage 13: ML 1 — Python & Data Basics. Progress is saved in this browser.
