Structural Pattern Matching (Match-Case) in Python

Structural Pattern Matching (Match-Case) in Python

Hello Everyone! Today we are going to learn about a cleaner, more efficient way to handle multiple fixed-value conditions in Python: Match-Case Statements.

When writing multi-condition code with if-elif-else, checking a long list of distinct matching values can become repetitive and visually cluttered. Python resolves this elegantly using the match and case structure, which works similarly to the switch-case statements found in languages like C.

1. Moving from if-elif-else to Match-Case

Let’s look at the problem of mapping a number to a weekday name. First, here is how we would implement it using our traditional conditional blocks:

The Traditional approach (if-elif-else):

number = int(input("Enter A Number: "))

if number == 1:
     print("Monday")
elif number == 2:
     print("Tuesday")
elif number == 3:
     print("Wednesday")
elif number == 4:
     print("Thursday")
elif number == 5:
     print("Friday")
elif number == 6:
     print("Saturday")
elif number == 7:
     print("Sunday")
else:
     print("Invalid number")

The Optimized approach (match-case):

Instead of repeating number == on every line, we pass the variable once to match and check its potential values via individual case blocks.

number = int(input("Enter A Number: "))

match number:
     case 1:
          print("Monday")
     case 2:
          print("Tuesday")
     case 3:
          print("Wednesday")
     case 4:
          print("Thursday")
     case 5:
          print("Friday")
     case 6:
          print("Saturday")    
     case 7:
          print("Sunday")
     case _:
          print("Invalid number.")

What is the underscore _? The case _: acts as the wildcard or fallback block. It is identical to the else block in conditional logic and will match absolutely anything if none of the explicit cases above it match.

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2. Match-Case with String Characters

Match-Case functions perfectly with characters and text strings too. Let’s see how we can map a singular text string input to verify an alphabet profile character:

char = input("Enter only 1 character: ")

match char:
     case "a":
          print("Vowel")
     case "e":
          print("Vowel")
     case "i":
          print("Vowel")
     case "o":
          print("Vowel")
     case "u":
          print("Vowel")
     case _:
          print("Consonant")

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3. Real-World Match-Case Scenarios

Scenario A: Cold Drink Volume Pricing Inventory Check

This structure checks an integer amount variable value to output precise manufacturing fluid volume packages available:

The Old if-elif Layout:

amount = int(input("Kitne rs laye ho?? "))

if amount == 20:
     print("200ML")
elif amount == 40:
     print("750ML")
elif amount == 50:
     print("1L")
elif amount == 90:
     print("2.25L")
else:
     print("No cold drink.")

The New match-case Layout:

match amount:
     case 20:
          print("200ML")
     case 40:
          print("750ML")
     case 50:
          print("1L")
     case 90:
          print("2.5L")
     case _:
          print("No cold drink.")

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Scenario B: Tracking Calendar Days in a Month

Here, we take a sequential index input integer representing a specific target month on the calendar (1-12) and read its matching total day limits.

month = int(input("Enter Month Number: "))

match month:
     case 1:
          print("31 Days")
     case 2:
          print("29 Days")
     case 3:
          print("31 Days")
     case 4:
          print("30 Days")
     case 5:
          print("31 Days")
     case 6:
          print("30 Days")
     case 7:
          print("31 Days")
     case 8:
          print("31 Days")
     case 9:
          print("30 Days")
     case 10:
          print("31 Days")
     case 11:
          print("30 Days")
     case 12:
          print("31 Days")
     case _:
          print("Invalid Month")