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Copy pathdict.py
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133 lines (111 loc) · 3.65 KB
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# empty object {}
alien_0 = {"color": "green", "points": 5}
print(alien_0["color"])
print(alien_0["points"])
new_point = alien_0["points"]
print(f"You just earned {new_point} points!")
# add new key-value pair
alien_0["x_position"] = 0
alien_0["y_position"] = 25
print(alien_0)
# modify value
alien_0["color"] = "yellow"
print(alien_0)
alien_0["speed"] = "fast"
if alien_0["speed"] == "slow":
x_increment = 1
elif alien_0["speed"] == "medium":
x_increment = 2
else:
x_increment = 3
alien_0["x_position"] = alien_0["x_position"] + x_increment
print(alien_0)
# delete key-value pair
del alien_0["points"]
print(alien_0.get("points", "Sorry, points is not exist")) # dict(key, default)
# print(alien_0["points"]) # KeyError: 'points'
print(alien_0)
favorite_languages = {
"jen": "python",
# 一种不错的做法是，在最后一个键值对后面也加上逗号，为以后添加键值对做好准备
"phil": "python",
}
for name in favorite_languages:
favorite_language = favorite_languages[name].title()
print(f"{name}'s favorite language is {favorite_language}")
# dict.items() D.items() -> a set-like object providing a view on D's items
print("============")
for name, language in favorite_languages.items():
print(f"{name}'s favorite language is {language.title()}")
items = favorite_languages.items()
keys = favorite_languages.keys()
values = favorite_languages.values()
# dict_items([('jen', 'python'), ('phil', 'python')]) type is <class 'dict_items'>
print(f"{items} type is {type(items)}")
# dict_keys(['jen', 'phil']) type is <class 'dict_keys'>
print(f"{keys} type is {type(keys)}")
# dict_values(['python', 'python']) type is <class 'dict_values'>
print(f"{values} type is {type(values)}")
# sorted
# sorted() # Return a new list containing all items from the iterable in ascending order.
# set
set() # set() -> new empty set object set(iterable) -> new set object
print(
set(favorite_languages.values())
) # {'python'} <= 花括号里面没有键值对，只有元素，称之为“集合”
aliens = []
for i in range(5):
if i % 2 == 0:
aliens.append(
{
"color": "green",
"speed": "slow",
"points": 5,
}
)
else:
aliens.append(
{
"color": "yellow",
"speed": "medium",
"points": 10,
}
)
print(aliens)
for alien in aliens[:3]:
if alien["color"] == "green":
alien["color"] = "yellow"
alien["speed"] = "medium"
alien["points"] = 10
# 必须得用 dict 的引用，通过 key 来修改 value，直接替换 dict 引用不会生效
# alien = {
# "color": "yellow",
# "speed": "medium",
# "points": 10,
# }
else:
alien["color"] = "red"
alien["speed"] = "fast"
alien["points"] = 15
# 必须得用 dict 的引用，通过 key 来修改 value，直接替换 dict 引用不会生效
# alien = {
# "color": "red",
# "speed": "fast",
# "points": 15,
# }
print("========")
print(aliens)
"""
当函数调用 print() 中的字符串很长，需要分成多行书写时：
1. 在合适的位置分行，在每行的末尾都加上"";
2. 对于除第一行外的其他各行，都在行首加上引号并缩进;
3. 这样，Python 将自动合并括号内的所有字符串；
"""
word = "hello"
print(
f"{word} it's too long {word} it's too long"
f" {word} it's too long {word} it's too long"
)
# A if condition == True else B
string = "hello" if 3 < 2 else "hi"
print(string)