Python Intro

列表 (List)

使用 join() 方法将列表中的所有元素连接成一个字符串。

list = ["this", "is", "an", "example", "of", "using", "join()", "method"]

seperator = " - "
new_list = seperator.join(list)

print(new_list)
# this - is - an - example - of - using - join() - method

使用 split() 方法将字符串拆分为列表。

print(new_list.split(seperator))
# ['this', 'is', 'an', 'example', 'of', 'using', 'join()', 'method']

集合 (Set)

intersection() , difference() , union()

set_1 = {1, 2, 3}
set_2 = {2, 3, 4}

print(set_1.intersection(set_2))
print(set_1.difference(set_2))
print(set_2.difference(set_1))
print(set_1.union(set_2))

#{2, 3}
#{1}
#{4}
#{1, 2, 3, 4}

字典 (Dictionary)

索引访问 VS get()

get() 在键不存在时会返回 None，而不是抛出 KeyError。

dict_1 = {
    "name": "4pril",
    "age": 24,
}

print(dict_1.get("phone") is None)
#True
print(dict_1["phone"])
#Traceback (most recent call last):
#  File "C:\Users\Administrator\PyCharmMiscProject\test.py", line 24, in <module>
#    print(dict_1["phone"])
#          ~~~~~~^^^^^^^^^
#KeyError: 'phone'

keys() , values() , items()

print(dict_1.keys())
#dict_keys(['name', 'age'])
print(dict_1.values())
#dict_values(['4pril', 24])
print(dict_1.items())
#dict_items([('name', '4pril'), ('age', 24)])

for k, v in dict_1.items():
    print(k, v, sep=" - ")

#name - 4pril
#age - 24

format()

name = '4pril'

print("name is {}".format(name))
# name is 4pril

* 和 **

def func(*args, **kwargs):
    print(args)
    print(kwargs)

func(1,2,3, name = '4pril', age = 24)
print('--------------------------------------')

func([1,2,3], {'name': '4pril', 'age': 24})
print('--------------------------------------')

func(*[1,2,3], **{'name': '4pril', 'age': 24})
print('--------------------------------------')


#(1, 2, 3)
#{'name': '4pril', 'age': 24}
#--------------------------------------
#([1, 2, 3], {'name': '4pril', 'age': 24})
#{}
#--------------------------------------
#(1, 2, 3)
#{'name': '4pril', 'age': 24}
#--------------------------------------