python中的字典那些事

python中字典的那些事（1）

我观看bilibili的视频，并总结了一些字典的知识，希望能帮到大家。

1.1一个简单的字典

创建一个空字典

people={}

添加键值对后的字典

# create a dictionnary
people={'first_name':'jignqin',
        'last_name':'mo',
        'city':'zhanjiag',
        'age':'7'
        }

1.2 使用字典

1.2.1访问字典中的值

print (people['first_name'])
print (people['last_name'])
print (people['city'])
print (people['age'])

1.2.2添加键-值对

people['hobby']='football'

1.2.3修改字典中的值

people['age']=8

1.2.4 删除键-值对（del）

del people['city']

1.3遍历字典

1.3.1 遍历所有的键-值对（items）

for key,value in people.items():
    print(key)
    print(value)

1.3.2 遍历字典中的所有键（keys）

for name in people.keys():
    print(name)

1.3.3 按顺序遍历字典中的所有键(sorted)

for name in sorted(people.keys()):
    print(name)

1.3.4 遍历字典中所有的值(values)

for v in people.values():
    print(v)

1.4 嵌套

1.4.1 字典列表（列表中包含字典）

# Make an empty list to store people in.
people = []

# Define some people, and add them to the list.
person = {
    'first_name': 'eric',
    'last_name': 'matthes',
    'age': 43,
    'city': 'sitka',
    }
people.append(person)

person = {
    'first_name': 'ever',
    'last_name': 'matthes',
    'age': 5,
    'city': 'sitka',
    }
people.append(person)

person = {
    'first_name': 'willie',
    'last_name': 'matthes',
    'age': 8,
    'city': 'sitka',
    }
people.append(person)

1.4.2 字典中存储列表

favorite_numbers = {
    'mandy': [42, 17],
    'micah': [42, 39, 56],
    'gus': [7, 12],
    }

for name, numbers in favorite_numbers.items():
    print("\n" + name.title() + " likes the following numbers:")
    for number in numbers:
        print("  " + str(number))

1.4.3 字典中存储字典

cities = {
    'santiago': {
        'country': 'chile',
        'population': 6158080,
        'nearby mountains': 'andes',
        },
    'talkeetna': {
        'country': 'alaska',
        'population': 876,
        'nearby mountains': 'alaska range',
        },
    'kathmandu': {
        'country': 'nepal',
        'population': 1003285,
        'nearby mountains': 'himilaya',
        }
    }

for city, city_info in cities.items():
    country = city_info['country'].title()
    population = city_info['population']
    mountains = city_info['nearby mountains'].title()

    print("\n" + city.title() + " is in " + country + ".")
    print("  It has a population of about " + str(population) + ".")
    print("  The " + mountains + " mountains are nearby.")

参考

习题