Python编程从入门到实践（4）学习笔记-if语句，字典

第五章 if语句

第六章 字典

# 第五章 if语句

# if语句 ==号是精确匹配
cars = ['bmw', 'audi', 'toyota', 'subaru']
for car in cars:
    if car == 'bmw':
        print(car.upper())
    else:
        print(car.title())

# 如果想无视大小写匹配可以先转小写再比
car.lower() == 'audi'

# 不等于 !=
requested_topping = 'mushrooms'
if requested_topping != 'anchovies':
    # 抓住鳀(咸水小鱼);
    print("Hold the anchovies")

# 等于 大于 小于
age = 19
age < 21
age <= 21
age > 21
age >= 21

# and or
age_0 = 22
age_1 = 18
age_0 >= 21 and age_1 >= 21
age_0 >= 21 or age_1 >= 21

# in
requested_topping = ['mushrooms', 'onions', 'pineapple']
# 精确匹配
if 'mushroomS' in requested_topping:
    print("True")
else:
    print("False")
# not in
if 'zz' not in requested_topping:
    print("zz is not in list ")

# 布尔表达式
game_active = True
can_edit = False

# 多路if elif else
age = 12

if age < 4:
    price = 0
elif age < 18:
    price = 5
elif age < 65:
    price = 10
else:
    price = 5

print(price)

# 列表不是空的检查
# 会走else 判断
requested_topping = []
# 至少含有1个元素才
if requested_topping:
    print("not empty")
else:
    print("yes is empty")

# 第六章 字典
alien_0 = {'color': 'green', 'point': 5}
print(alien_0['color'])
print(alien_0['point'])
print(alien_0)

# 加了2对键值对
alien_0['x_position'] = 0
alien_0['y_position'] = 25
print(alien_0)

# 空字典
alien_0 = {}
alien_0['color'] = 'green'
alien_0['points'] = 5
print(alien_0)

# 修改键值对
alien_0['color'] = 'red'
print(alien_0)

# 删除键值对
del alien_0['color']
print(alien_0)

favorite_languages = {
    'jen': 'python',
    'sarah': 'c',
    'edward': 'ruby',
    'phil': 'python',
}
# 拼接可以换行
print("sarah's favorite language is " +
      favorite_languages['sarah'].title() +
      ".")

# 遍历字典
for name, language in favorite_languages.items():
    print(name.title() + "'s favorite language is " +
          language.title() + ".")

# 提取key
for name in favorite_languages.keys():
    print(name.title())

# 排序 favorite_languages.keys的 .keys可以省略
for name in sorted(favorite_languages):
    print(name.title())

# 提取values
for language in favorite_languages.values():
    print(language.title())

# 提取values 去重复，进一个set集合
print("去除重复")
for language in set(favorite_languages.values()):
    print(language.title())

# 字典列表 P93
aliens = []
for alien_number in range(30):
    new_alien = {'color': 'green', 'points': 5, 'speed': 'slow'}
    aliens.append(new_alien)

for alien in aliens[:5]:
    print(alien)
print("Totle number of aliens :" + str(len(aliens)))

# 字典中存列表
pizza = {
    'crust': 'thick',
    'toppings': ['mushrooms', 'extra cheese']
}

# 字典中value是多值
favorite_languages = {
    'jen': ['python', 'ruby'],
    'sarah': ['c'],
    'edward': ['ruby', 'go'],
    'phil': ['python', 'haskell'],
}

for k, v in favorite_languages.items():
    print(name.title() + "'s favorite language are:")
    for language in v:
        print("\t" + language.title())

#在字典中存字典
users = {
    'aeinstein':{
        'first':'albert',
        'last':'einstein',
        'location':'princeton',
    },
    'mucurie':{
        'first':'marie',
        'last':'curie',
        'location':'paris',
    },
}