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Python zip 函数详解：用法、应用场景与高级技巧（中英双语）

news 来源：原创 2025/5/2 7:32:09

Python `zip` 函数详解：用法、应用场景与高级技巧

在 Python 编程中，zip() 是一个非常实用的内置函数，它可以并行迭代多个可迭代对象，并将对应元素组合成元组。无论是在数据处理、遍历多个列表，还是在复杂的数据结构转换中，zip() 都能大大提高代码的简洁性和可读性。

本文将详细介绍：

zip() 的基本用法
zip() 的常见应用场景
zip() 的高级用法，包括解压、多重 zip()、结合 enumerate() 等

1. `zip()` 的基本用法

1.1 语法

zip(*iterables)

iterables：一个或多个可迭代对象，如列表、元组、字符串、字典、集合等。
zip() 将按索引位置将多个可迭代对象的元素组合成元组。
返回值是一个 zip 对象，它是一个惰性迭代器，只有在遍历时才会生成元素，避免了不必要的内存占用。

1.2 基本示例

names = ["Alice", "Bob", "Charlie"]
ages = [25, 30, 35]

zipped = zip(names, ages)  # 创建 zip 对象
print(list(zipped))  # 转换为列表查看结果

输出：

[('Alice', 25), ('Bob', 30), ('Charlie', 35)]

解析：

zip() 按索引将 names 和 ages 的元素配对，形成元组。
结果是一个列表，每个元素是 (name, age) 形式的元组。

2. `zip()` 的常见应用场景

2.1 并行遍历多个列表

在遍历多个等长列表时，zip() 可以避免使用 range(len(x)) 这样的索引操作，使代码更加 Pythonic。

names = ["Alice", "Bob", "Charlie"]
ages = [25, 30, 35]

for name, age in zip(names, ages):
    print(f"{name} is {age} years old.")

输出：

Alice is 25 years old.
Bob is 30 years old.
Charlie is 35 years old.

相比 for i in range(len(names))，zip() 的写法更简洁直观。

2.2 解压（Unzipping）数据

zip() 的逆操作可以使用 zip(*)，即 zip(*zipped_data)，用于将多个列表解压回原来的形式。

zipped_data = [('Alice', 25), ('Bob', 30), ('Charlie', 35)]
names, ages = zip(*zipped_data)

print(names)  # ('Alice', 'Bob', 'Charlie')
print(ages)   # (25, 30, 35)

解析：

zip(*zipped_data) 相当于 zip(('Alice', 'Bob', 'Charlie'), (25, 30, 35))。
zip(*iterables) 通过 行列互换，将 zipped_data 解压成两个元组。

2.3 结合 `enumerate()` 使用

在 zip() 的基础上，我们可以使用 enumerate() 获取元素的索引，例如：

names = ["Alice", "Bob", "Charlie"]
ages = [25, 30, 35]

for i, (name, age) in enumerate(zip(names, ages)):
    print(f"{i}: {name} is {age} years old.")

输出：

0: Alice is 25 years old.
1: Bob is 30 years old.
2: Charlie is 35 years old.

解析：

enumerate(zip(names, ages)) 让 zip 迭代出的 (name, age) 对应的索引 i 也能获取到。

💡 实际案例：在 PyTorch 或 TensorFlow 训练过程中，我们经常遍历多个损失函数：

for i, (loss_func, optimizer) in enumerate(zip(loss_functions, optimizers)):
    print(f"Training Step {i}: Using {loss_func.__name__} with {optimizer.__class__.__name__}")

3. `zip()` 的高级用法

3.1 处理长度不等的迭代器

(1) `zip()` 的默认行为：截断

如果 zip() 处理的迭代对象长度不同，它会按最短的迭代对象截断：

names = ["Alice", "Bob"]
ages = [25, 30, 35]

print(list(zip(names, ages)))  # [('Alice', 25), ('Bob', 30)]

35 没有配对对象，因此被忽略。

(2) 使用 `itertools.zip_longest()`

如果希望填充缺失值，可以使用 itertools.zip_longest()：

from itertools import zip_longest

names = ["Alice", "Bob"]
ages = [25, 30, 35]

print(list(zip_longest(names, ages, fillvalue="N/A")))

输出：

[('Alice', 25), ('Bob', 30), ('N/A', 35)]

zip_longest() 会用 "N/A" 填充缺失值。

3.2 `zip()` 与字典

(1) 创建字典

keys = ["name", "age", "city"]
values = ["Alice", 25, "New York"]

person = dict(zip(keys, values))
print(person)

输出：

{'name': 'Alice', 'age': 25, 'city': 'New York'}

解析：

zip(keys, values) 组合键值对。
dict() 将其转换为字典。

(2) 遍历字典的 `key-value` 对

person = {"name": "Alice", "age": 25, "city": "New York"}

for key, value in zip(person.keys(), person.values()):
    print(f"{key}: {value}")

3.3 `zip()` 用于矩阵转置

在处理二维数据时，zip(*matrix) 可以实现矩阵转置：

matrix = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
]

transposed = list(zip(*matrix))
print(transposed)

输出：

[(1, 4, 7), (2, 5, 8), (3, 6, 9)]

解析：

zip(*matrix) 让每列变成一行，实现行列互换。

4. 结论

用法	示例代码
基本用法	`zip(names, ages)`
并行遍历多个列表	`for name, age in zip(names, ages):`
解压数据	`names, ages = zip(*zipped_data)`
结合 `enumerate()`	`for i, (name, age) in enumerate(zip(names, ages)):`
处理长度不等的迭代器	`zip_longest(names, ages, fillvalue="N/A")`
字典创建	`dict(zip(keys, values))`
矩阵转置	`zip(*matrix)`

🚀 zip() 是 Python 数据处理和迭代优化的重要工具，掌握它能让你的代码更加简洁高效！

Python `zip()` Function: Usage, Applications, and Advanced Techniques

The zip() function in Python is a powerful built-in function that allows you to iterate over multiple iterables in parallel by combining their elements into tuples. It is widely used in data processing, iterating over multiple lists, matrix manipulations, and dictionary operations.

In this article, we will explore:

The basic usage of zip()
Common real-world applications
Advanced techniques such as unpacking, handling uneven iterables, and combining zip() with enumerate()

1. Understanding `zip()`

1.1 Syntax

zip(*iterables)

iterables: One or more iterable objects (e.g., lists, tuples, dictionaries, sets).
Returns: A zip object, which is an iterator that yields tuples containing the corresponding elements from each iterable.

1.2 Basic Example

names = ["Alice", "Bob", "Charlie"]
ages = [25, 30, 35]

zipped = zip(names, ages)  # Creating a zip object
print(list(zipped))  # Convert to a list to view results

Output:

[('Alice', 25), ('Bob', 30), ('Charlie', 35)]

Explanation:

zip() pairs elements from names and ages by index into tuples.

2. Common Applications of `zip()`

2.1 Iterating Over Multiple Lists in Parallel

Instead of using range(len(x)), zip() provides a more readable way to iterate through multiple lists simultaneously.

names = ["Alice", "Bob", "Charlie"]
ages = [25, 30, 35]

for name, age in zip(names, ages):
    print(f"{name} is {age} years old.")

Output:

Alice is 25 years old.
Bob is 30 years old.
Charlie is 35 years old.

This avoids using index-based loops, making the code cleaner and more Pythonic.

2.2 Unpacking (Unzipping) Data

The reverse of zip() can be achieved using zip(*), which separates the combined tuples back into individual sequences.

zipped_data = [('Alice', 25), ('Bob', 30), ('Charlie', 35)]
names, ages = zip(*zipped_data)

print(names)  # ('Alice', 'Bob', 'Charlie')
print(ages)   # (25, 30, 35)

Explanation:

zip(*zipped_data) unpacks the list of tuples into two separate tuples.

2.3 Using `zip()` with `enumerate()`

By combining zip() with enumerate(), we can get both the index and the values:

names = ["Alice", "Bob", "Charlie"]
ages = [25, 30, 35]

for i, (name, age) in enumerate(zip(names, ages)):
    print(f"{i}: {name} is {age} years old.")

Output:

0: Alice is 25 years old.
1: Bob is 30 years old.
2: Charlie is 35 years old.

Use Case:

When iterating over multiple iterables while keeping track of the index.

3. Advanced `zip()` Techniques

3.1 Handling Unequal Length Iterables

(1) Default Behavior: Truncation

By default, zip() stops at the shortest iterable.

names = ["Alice", "Bob"]
ages = [25, 30, 35]

print(list(zip(names, ages)))  # [('Alice', 25), ('Bob', 30)]

Notice:

The last element (35) is ignored because zip() truncates to the shortest iterable.

(2) Using `itertools.zip_longest()`

To handle missing values, use itertools.zip_longest():

from itertools import zip_longest

names = ["Alice", "Bob"]
ages = [25, 30, 35]

print(list(zip_longest(names, ages, fillvalue="N/A")))

Output:

[('Alice', 25), ('Bob', 30), ('N/A', 35)]

zip_longest() fills missing values with "N/A" instead of truncating.

3.2 Using `zip()` with Dictionaries

(1) Creating a Dictionary

keys = ["name", "age", "city"]
values = ["Alice", 25, "New York"]

person = dict(zip(keys, values))
print(person)

Output:

{'name': 'Alice', 'age': 25, 'city': 'New York'}

Explanation:

zip(keys, values) pairs keys with corresponding values.
dict() converts the pairs into a dictionary.

(2) Iterating Over a Dictionary

person = {"name": "Alice", "age": 25, "city": "New York"}

for key, value in zip(person.keys(), person.values()):
    print(f"{key}: {value}")

This allows controlled iteration over dictionary keys and values.

3.3 Using `zip()` for Matrix Transposition

zip(*matrix) efficiently transposes a matrix:

matrix = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
]

transposed = list(zip(*matrix))
print(transposed)

Output:

[(1, 4, 7), (2, 5, 8), (3, 6, 9)]

Explanation:

zip(*matrix) swaps rows and columns, effectively transposing the matrix.

4. Conclusion

Use Case	Example
Basic Usage	`zip(names, ages)`
Parallel Iteration	`for name, age in zip(names, ages):`
Unpacking Data	`names, ages = zip(*zipped_data)`
Using with `enumerate()`	`for i, (name, age) in enumerate(zip(names, ages)):`
Handling Unequal Lengths	`zip_longest(names, ages, fillvalue="N/A")`
Creating a Dictionary	`dict(zip(keys, values))`
Transposing a Matrix	`zip(*matrix)`