python的zip函数

zip() 函数用于将可迭代的对象作为参数，将对象中对应的元素打包成一个个元组，然后返回由这些元组组成的列表。

first_name = ['Joe','Earnst','Thomas','Martin','Charles']

last_name = ['Schmoe','Ehlmann','Fischer','Walter','Rogan','Green']

age = [23, 65, 11, 36, 83]

print(list(zip(first_name,last_name, age)))

# Output
#
# [('Joe', 'Schmoe', 23), ('Earnst', 'Ehlmann', 65), ('Thomas', 'Fischer', 11), ('Martin', 'Walter', 36), ('Charles', 'Rogan', 83)]

使用zip函数的优势之一在于提高循环语句的可读性：

first_name = ['Joe','Earnst','Thomas','Martin','Charles']
last_name = ['Schmoe','Ehlmann','Fischer','Walter','Rogan','Green']
age = [23, 65, 11, 36, 83]

for first_name, last_name, age in zip(first_name, last_name, age):
    print(f"{first_name} {last_name} is {age} years old")

# Output
#
# Joe Schmoe is 23 years old
# Earnst Ehlmann is 65 years old
# Thomas Fischer is 11 years old
# Martin Walter is 36 years old
# Charles Rogan is 83 years old

如果各个迭代器的元素个数不一致，则返回列表长度与最短的对象相同。

a = [1,2,3]

b = [4,5,6,7,8]

print(list(zip(a,b)))

# Output
#
# [(1, 4), (2, 5), (3, 6)]

利用 * 号操作符，可以将元组解压为列表。

full_name_list = [('Joe', 'Schmoe', 23),
                  ('Earnst', 'Ehlmann', 65),
                  ('Thomas', 'Fischer', 11),
                  ('Martin', 'Walter', 36),
                  ('Charles', 'Rogan', 83)]

first_name, last_name, age = list(zip(*full_name_list))
print(f"first name: {first_name}\nlast name: {last_name} \nage: {age}")

# Output

# first name: ('Joe', 'Earnst', 'Thomas', 'Martin', 'Charles')
# last name: ('Schmoe', 'Ehlmann', 'Fischer', 'Walter', 'Rogan')
# age: (23, 65, 11, 36, 83)