Python Tuples: คู่มือครบวงจร สร้าง, เข้าถึง, Slicing, Operations

Tuple ใน Python เป็น Ordered, Immutable Collection สร้างด้วย Parentheses () และ Comma ,

1. สร้าง Tuple

# Multiple items
colors = ("red", "green", "blue")
print(colors)  # ('red', 'green', 'blue')

# Single item - ต้องมี Comma!
single = ("red",)      # ✅ Tuple
not_tuple = ("red")    # ❌ String!

# Empty Tuple
empty = ()

# Tuple Constructor
colors = tuple(["red", "green", "blue"])

2. เข้าถึง Items

colors = ("red", "green", "blue", "yellow", "orange", "white")

# Index (0-based)
colors[0]    # 'red'
colors[2]    # 'blue'

# Negative Index
colors[-1]   # 'white'
colors[-2]   # 'orange'

# Slicing [start:stop:step] - คืนค่าเป็น Tuple ด้วย
colors[1:4]      # ('green', 'blue', 'yellow')
colors[::2]      # ('red', 'blue', 'orange')
colors[::-1]     # ('white', 'orange', 'yellow', 'blue', 'green', 'red')

3. วนลูป Tuple

colors = ("red", "green", "blue", "orange")

for color in colors:
    print(color)

# With Index
for i, color in enumerate(colors):
    print(f"{i}: {color}")

4. Tuple Operations

Concatenation (+)

colors = ("red", "green", "blue")
numbers = (1, 2, 3)
combined = colors + numbers
# ('red', 'green', 'blue', 1, 2, 3)

Repetition (*)

("a", "b") * 3  # ('a', 'b', 'a', 'b', 'a', 'b')

Membership Test

"red" in colors      # True
"purple" not in colors  # True

Length และ Count

len(colors)           # 4
colors.count("red")   # 1
colors.index("blue")  # 2 (หา Index แรกที่เจอ)

5. Immutability (ไม่สามารถเปลี่ยนแปลงได้)

colors = ("red", "green", "blue")
# colors[0] = "yellow"  # ❌ TypeError: 'tuple' object does not support item assignment

# แต่มัน Mutable Object ภายใน Tuple ได้
mixed = ([1, 2], "hello")
mixed[0].append(3)  # ✅ List ภายในเปลี่ยนได้
print(mixed)        # ([1, 2, 3], 'hello')

6. ลบ Tuple

colors = ("red", "green", "blue")
del colors
# print(colors)  # NameError: name 'colors' is not defined

7. Tuple Unpacking (Pattern Matching)

# Basic Unpacking
colors = ("red", "green", "blue")
r, g, b = colors
print(r, g, b)  # red green blue

# Extended Unpacking (Python 3+)
numbers = (1, 2, 3, 4, 5)
first, *middle, last = numbers
print(first)   # 1
print(middle)  # [2, 3, 4] (เป็น List!)
print(last)    # 5

# Swap Variables
a, b = 10, 20
a, b = b, a
print(a, b)  # 20 10

8. NamedTuple (Readable, Lightweight)

from collections import namedtuple
from typing import NamedTuple

# Classic
Point = namedtuple('Point', ['x', 'y'])
p = Point(10, 20)
print(p.x, p.y)  # 10 20

# Modern (Python 3.6+) - Type Hints
class Point(NamedTuple):
    x: int
    y: int

p = Point(10, 20)
print(p.x, p.y)  # 10 20

เมื่อไหร่ควรใช้ Tuple แทน List?

บทความเกี่ยวข้อง

• Python Lists
• Python Sets
• Python Dictionaries