Python3 运算符与基本数据类型

>>> a = 10
>>> b = 2

>>> print("a + b =", a + b)
a + b = 12

>>> print("a - b =", a - b)
a - b = 8

>>> print("a * b =", a * b)
a * b = 20

>>> print("a / b =", a / b)
a / b = 5.0

>>> print("a % b =", a % b)
a % b = 0

>>> print("a ** b =", a ** b)
a ** b = 100

>>> print("a // b =", a // b)
a // b = 5

>>> a = 23
>>> b = 17

>>> if (a == b):
...     print("a == b")
... elif (a != b):
...     print("a != b")
... elif (a > b):
...     print("a > b")
... elif (a < b):
...     print("a < b")
... elif (a >= b):
...     print("a >= b")
... elif (a <= b):
...     print("a <= b")
... 
a != b

>>> a = 10
>>> b = 3
>>> c = 0

>>> c += a
>>> print("c =", c)
c = 10

>>> c *= b
>>> print("c =", c)
c = 30

>>> c /= b
>>> print("c =", c)
c = 10.0

>>> c **= b
>>> print("c =", c)
c = 1000.0

>>> c //= b
>>> print("c =", c)
c = 333.0

# a 和 b 都为 True
>>> a = 20
>>> b = 10

>>> print("a and b =", a and b)
a and b = 10

>>> print("a or b =", a or b)
a or b = 20


# a 为 True， b 为 False
>>> a = 20
>>> b = 0

>>> print("a and b =", a and b)
a and b = 0

>>> print("a or b =", a or b)
a or b = 20


# a 为 False，b 为 True
>>> a = 0
>>> b = 10

>>> print("a and b =", a and b)
a and b = 0

>>> print("a or b =", a or b)
a or b = 10

>>> a = 60          # 60 = 0011 1100 
>>> b = 13          # 13 = 0000 1101 

>>> print("a & b =", a & b)
a & b = 12               # 0000 1100 = 12

>>> print("a | b =", a | b)
a | b = 61               # 0011 1101 = 61

>>> print("a ^ b =", a ^ b)
a ^ b = 49               # 0011 0001 = 49

>>> print("~a =", ~a)
~a = -61                 # 1100 0011 = -61

>>> print("a << 2 =", a << 2)
a << 2 = 240             # 1111 0000 = 240

>>> print("a >> 2 =", a >> 2)
a >> 2 = 15              # 0000 1111 = 15

>>> a = 7
>>> b = 15
>>> lists = [1, 3, 5, 7, 9]

>>> if (a in lists):
...     print("a 在列表 lists 中")
... else:
...     print("a 不在列表 lists 中。")
... 
a 在列表 lists 中

>>> if (b not in lists):
...     print("b 不在列表 lists 中")
... else:
...     print("b 在列表 lists 中")
... 
b 不在列表 lists 中

>>> a = 20
>>> b = 10
>>> c = 15
>>> d = 5

>>> print("(a + b) * c / d =", (a + b) * c / d)
(a + b) * c / d = 90.0

>>> print("((a + b) * c) / d =", ((a + b) * c) / d)
((a + b) * c) / d = 90.0

>>> print("(a + b) * (c / d) =", (a + b) * (c / d))
(a + b) * (c / d) = 90.0

>>> print("a + (b * c) / d =", a + (b * c) / d)
a + (b * c) / d = 50.0

>>> print ("abs(-40) =", abs(-40))
abs(-40) = 40

>>> import math

>>> print ("math.ceil(-45.17) =", math.ceil(-45.17))
math.ceil(-45.17) = -45

>>> print ("math.ceil(99.15) =", math.ceil(99.15))
math.ceil(99.15) = 100

>>> import math

>>> print ("math.floor(-45.17) =", math.floor(-45.17))
math.floor(-45.17) = -46

>>> print ("math.floor(99.15) =", math.floor(99.15))
math.floor(99.15) = 99

>>> import math 

>>> print ("math.exp(math.pi) =", math.exp(math.pi))
math.exp(math.pi) = 23.140692632779267

>>> print ("max(-80, -20, -10) =", max(-80, -20, -10))
max(-80, -20, -10) = -10

>>> print ("min(-80, -20, -10) =", min(-80, -20, -10))
min(-80, -20, -10) = -80

>>> import math 

>>> print ("math.modf(math.pi) =", math.modf(math.pi))
math.modf(math.pi) = (0.14159265358979312, 3.0)

>>> import math

>>> print ("round(math.pi, 2) =", round(math.pi, 2))
round(math.pi, 2) = 3.14

>>> round(0.5)
0

>>> round(1.5)
2

>>> round(0.50001)
1

>>> import math

>>> print ("math.sqrt(9) =", math.sqrt(9))
math.sqrt(9) = 3.0

>>> import math

>>> print ("math.pow(100, 2) =", math.pow(100, 2))
math.pow(100, 2) = 10000.0

>>> import random

>>> print ("从 range(100) 返回一个随机数 =",random.choice(range(100)))
从 range(100) 返回一个随机数 = 29

>>> print ("从列表中 [1, 2, 3, 5, 9]) 返回一个随机元素 =", random.choice([1, 2, 3, 5, 9]))
从列表中 [1, 2, 3, 5, 9] 返回一个随机元素 = 1

>>> import random

>>> print("random() =", random.random())
random() = 0.5426028101355577

>>> import random

>>> print("randint(1,10) =", random.randint(1,10))
10

>>> import math 

>>> print ("math.sin(math.pi) =",  math.sin(math.pi))
math.sin(math.pi) = 1.2246467991473532e-16

>>> print ("math.sin(90) =", math.sin(90))
math.sin(90) = 0.8939966636005579

>>> s = "hello PYTHON"
>>> s.capitalize()
'Hello python'

>>> s = "123 Hello Python"
>>> s.capitalize()
'123 hello python'

>>> s = "https://www.python.org"
>>> sub = "o"

>>> s.count(sub)
2

>>> sub = "t"
>>> s.count(sub, 10, 20)
1

>>> s = "-"                                # 连接串
>>> seq = ('P', 'Y', 'T', 'H', 'O', 'N')   # 字符串序列

>>> s.join(seq)
'P-Y-T-H-O-N'

>>> s = "I Love it."
>>> len(s)
10

>>> s = "www.baidu.com"
>>> s.replace('baidu.com', 'python.org')
'www.python.org'

>>> s = "this is string example....wow!!!"
>>> s.replace('is', 'was', 2)
'thwas was string example....wow!!!'

s = "this is string example....wow!!!"


# 以空格为分隔符
>>> s.split()
['this', 'is', 'string', 'example....wow!!!']


# 以 w 为分隔符
>>> s.split('w')
['this is string example....', 'o', '!!!']


# 以 i 为分隔符，且分隔次数为 1 
>>> s.split('i', 1)
['th', 's is string example....wow!!!']

>>> s = 'abca'


# 从下标 0 开始，查找在字符串里第一个出现的子串
>>> s.find('a')
0


# 从下标 1 开始，查找在字符串里第一个出现的子串
>>> s.find('a', 1) 
3


# 查找不到返回 -1
>>> s.find('3')  
-1

>>> s1 = "this is really a string example....wow!!!"
>>> s2 = "is"

>>> s1.rfind(s2)
5

>>> s1.find(s2)
2

>>> s1 = "Runoob example....wow!!!"
>>> s2 = "exam"

>>> s1.index(s2)
7

>>> s1.index(s2, 5)
7

>>> s1.index(s2, 10)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: substring not found

>>> s1 = "this is really a string example....wow!!!"
>>> s2 = "is"

>>> s1.rindex(s2)
5

>>> s1.rindex(s2, 10)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: substring not found

>>> s = "     this is string example....wow!!!     "

>>> s.rstrip()
'     this is string example....wow!!!'


>>> s = "*****this is string example....wow!!!*****"

>>> s.rstrip('*')
'*****this is string example....wow!!!'

>>> s = "     this is string example....wow!!!     "

>>> s.lstrip()
'this is string example....wow!!!     '


>>> s = "88888888this is string example....wow!!!8888888"

>>> s.lstrip('8')
'this is string example....wow!!!8888888'

# 删除指定字符串 '*'

>>> s = "*****this is **string** example....wow!!!*****"

>>> s.strip( '*' )
'this is **string** example....wow!!!'


# 删除字符序列 '12'

>>> s = "123abcrunoob321"

>>> s.strip('12')
'3abcrunoob3'

>>> s = "www.baidu.com"

>>> s.upper()
'WWW.BAIDU.COM'

>>> s = "ORACLE ACE"

>>> s.lower()
'oracle ace'

>>> s = "www.baidu.com"

>>> max(s)
'w'

>>> s = "www.baidu.com"

>>> min(s)
'.'

>>> s = "www.baidu.com"

>>> s.isalnum()
False

>>> s = "www.baidu.com"

>>> s.isalpha()
False


>>> s = "baidu"

>>> s.isalpha()
True

>>> s = "1 3 5 7 9"

>>> s.isdigit()
False


>>> s = "123"

>>> s.isdigit()
True

>>> s = "www.baidu.com"

>>> s.islower()
True

>>> s = "WWW.BAIDU.COM"

>>> s.islower()
True

>>> s = 'Runoob example....wow!!!'
>>> suffix='!!'

>>> s.endswith(suffix)
True

>>> s.endswith(suffix, 30, 100)
False


>>> s = 'Runoob example....wow!!!'
>>> suffix='run'

>>> s.endswith(suffix)
False

>>> s = "字符串"
>>> s_utf8 = s.encode('UTF-8')
>>> s_gbk = s.encode('GBK')

>>> print ("UTF-8 编码：", s_utf8)
UTF-8 编码： b'\xe5\xad\x97\xe7\xac\xa6\xe4\xb8\xb2'

>>> print ("GBK 编码：", s_gbk)
GBK 编码： b'\xd7\xd6\xb7\xfb\xb4\xae'

>>> s = "字符串"
>>> s_utf8 = s.encode('UTF-8')
>>> s_gbk = s.encode('GBK')

>>> print (s)
字符串

>>> print ("UTF-8 编码：", s_utf8)
UTF-8 编码： b'\xe5\xad\x97\xe7\xac\xa6\xe4\xb8\xb2'

>>> print ("GBK 编码：", s_gbk)
GBK 编码： b'\xd7\xd6\xb7\xfb\xb4\xae'

>>> print("UTF-8 解码：", s_utf8.decode('UTF-8', 'strict'))
UTF-8 解码： 字符串

>>> print("GBK 解码：", s_gbk.decode('GBK', 'strict'))
GBK 解码： 字符串

>>> print('hello %s and %s' %('Python', 'Oracle'))
hello Python and Oracle

>>> print('hello %(first)s and %(second)s' %{'first':'Python', 'second':'Oracle'})
hello Python and Oracle

>>> print('hello {0} and {1}'.format('Python', 'Oracle'))
hello Python and Oracle

>>> print('hello {first} and {second}'.format(first='Python', second='Oracle'))
hello Python and Oracle

>>> letter = 'abcd'

>>> letter[0]
'a'

>>> letter[-1]
'd'

>>> letter = 'abcdefghijklmnopqrstuvwxyz'

>>> letter[-3:]
'xyz'

>>> letter[::5]
'afkpuz'

>>> letter[::-1]
'zyxwvutsrqponmlkjihgfedcba'

>>> s = "this is my string"

>>> s.split()
['this', 'is', 'my', 'string']

>>> type(s.split())
<class 'list'>
>>> 

>>> s = '<a href="www.baidu.com">baidu</a>'

>>> s.split('"')[1].split('.')
['www', 'baidu', 'com']

>>> s = "this is my string"

>>> s.split(maxsplit=1)
['this', 'is my string']

Name,Phone,Address
Mike Smith,15554218841,123 Nice St, Roy, NM, USA
Anita Hernandez,15557789941,425 Sunny St, New York, NY, USA
Guido van Rossum,315558730,Science Park 123, 1980 XG Amsterdam, NL

[
    ['Mike Smith', '15554218841', '123 Nice St, Roy, NM, USA'],
    ['Anita Hernandez', '15557789941', '425 Sunny St, New York, NY, USA'],
    ['Guido van Rossum', '315558730', 'Science Park 123, 1980 XG Amsterdam, NL']
]

>>> s = """Name,Phone,Address
Mike Smith,15554218841,123 Nice St, Roy, NM, USA
Anita Hernandez,15557789941,425 Sunny St, New York, NY, USA
Guido van Rossum,315558730,Science Park 123, 1980 XG Amsterdam, NL"""

>>> def str_split(unsplit):
...     results = []
...     for line in unsplit.split('\n')[1:]:
...         results.append(line.split(',', maxsplit=2))
...     return results
...

>>> print(str_split(s))
[['Mike Smith', '15554218841', '123 Nice St, Roy, NM, USA'], ['Anita Hernandez', '15557789941', '425 Sunny St, New York, NY, USA'], ['Guido van Rossum', '315558730', 'Science Park 123, 1980 XG Amsterdam, NL']]

>>> s1 = "hello"
>>> s2 = "world"

>>> s = s1 + ' ' +  s2

>>> s
'hello world'

>>> s = "python"

>>> ','.join(s)
'p,y,t,h,o,n'

>>> li = ['hello', 'python']

>>> ','.join(li)
'hello,python'

>>> import sys

>>> sys.getdefaultencoding()
'utf-8'

>>> '字符串'.encode()
b'\xe5\xad\x97\xe7\xac\xa6\xe4\xb8\xb2'

>>> b'\xe5\xad\x97\xe7\xac\xa6\xe4\xb8\xb2'.decode('utf-8')
'字符串'

>>> l1 = ['Google', 'Baidu', 1997, 2000]
>>> l2 = [1, 3, 5, 6, 7 ]

>>> print ("l1[0] =", l1[0])
l1[0] = Google

>>> print ("l2[1:3] =", l2[1:3])
l2[1:3] = [3, 5]

>>> l = ['Google', 'Baidu', 1997, 2000]

>>> print ("第三个元素为 =", l[2])
第三个元素为 = 1997

>>> l[2] = 2001

>>> print ("更新后的第三个元素为 : ", l[2])
更新后的第三个元素为 :  2001

>>> l = ['Google', 'Baidu', 1997, 2000]

>>> print ("原始列表 =", l)
原始列表 = ['Google', 'Baidu', 1997, 2000]

>>> del l[2]

>>> print ("删除第三个元素 =", l)
删除第三个元素 = ['Google', 'Baidu', 2000]

>>> l = ['Google', 'Baidu', 'Safari']

>>> l[2]
'Safari'

>>> l[-2]
'Baidu'

>>> l[1:]
['Baidu', 'Safari']

>>> l += ['firefox']

>>> l
['Google', 'Baidu', 'Safari', 'firefox']

>>> l1 = ['a', 'b', 'c']

>>> l2 = [1, 2, 3]

>>> l3 = [l1, l2]

>>> l3 
[['a', 'b', 'c'], [1, 2, 3]]

>>> l1 = ['Google', 'Baidu', 'Safari']

>>> print("len(l1) =", len(l1))
len(l1) = 3


>>> l2 = list(range(10))

>>> print("len(l2) =", len(l2))
len(l2) = 10

>>> l1, l2 = ['Google', 'Baidu', 'Safari'], [3, 7, 9]

>>> print ("l1 最大元素值 =", max(l1))
l1 最大元素值 = Safari

>>> print ("l2 最大元素值 =", max(l2))
l2 最大元素值 = 9

>>> l1, l2 = ['Google', 'Baidu', 'Safari'], [3, 7, 9]

>>> print ("l1 最小元素值 =", min(l1))
l1 最小元素值 = Baidu

>>> print ("l2 最小元素值 =", min(l2))
l2 最小元素值 = 3

>>> t = (123, 'Google', 'Baidu', 'Safari')

>>> l1 = list(t)

>>> print ("列表元素 =", l1)
列表元素 = [123, 'Google', 'Baidu', 'Safari']


>>> s = "Hello World"

>>> l2 = list(s)

>>> print ("列表元素 =", l2)
列表元素 = ['H', 'e', 'l', 'l', 'o', ' ', 'W', 'o', 'r', 'l', 'd']

>>> l = ['Google', 'Baidu', 'Safari']

>>> l.append('firefox')

>>> print ("更新后的列表 =", l)
更新后的列表 = ['Google', 'Baidu', 'Safari', 'firefox']

>>> l = [123, 'Google', 'Baidu', 'Safari', 123];

>>> print ("123 元素个数 =", l.count(123))
123 元素的个数 = 2

>>> print ("'Safari' 元素个数 =", l.count('Safari'))
'Safari' 元素的个数 = 1

>>> language = ['French', 'English', 'German']

>>> language_tuple = ('Spanish', 'Portuguese')

>>> language_set = {'Chinese', 'Japanese'}

>>> language.extend(language_tuple)

>>> print('新列表 =', language)
新列表 = ['French', 'English', 'German', 'Spanish', 'Portuguese']

>>> language.extend(language_set)

>>> print('新列表 =', language)
新列表 = ['French', 'English', 'German', 'Spanish', 'Portuguese', 'Japanese', 'Chinese']

>>> l = ['Google', 'Baidu', 'Safari']

>>> l.index('Safari')
2

>>> l.index('Firefox')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: 'Firefox' is not in list

>>> l = ['Google', 'Baidu', 'Safari']

>>> l.insert(1, 'Firefox')

>>> l
['Google', 'Firefox', 'Baidu', 'Safari']

>>> l = ['Google', 'Baidu', 'Safari']

>>> l.pop()
'Safari'

>>> l
['Google', 'Baidu']

>>> l.pop(1)
'Baidu'

>>> l
['Google']

>>> l = ['Google', 'Baidu', 'Safari', 'Google']

>>> l.remove('Google')

>>> l
['Baidu', 'Safari', 'Google']

>>> l.remove('Baidu')

>>> l
['Safari', 'Google']

>>> l = ['Google', 'Baidu', 'Safari']

>>> l.reverse()

>>> l  
['Safari', 'Baidu', 'Google']

# 默认升序

>>> l = [1, 5, 23, 19, 7]

>>> l.sort()

>>> l
[1, 5, 7, 19, 23]


# 降序
>>> l = [1, 5, 23, 19, 7]

>>> l.sort(reverse=True)

>>> l
[23, 19, 7, 5, 1]

>>> lt = [('a',3),('b',10),('c',1),('d',5),('e',16)]
>>> print(lt)
[('a', 3), ('b', 10), ('c', 1), ('d', 5), ('e', 16)]


# 自定义排序函数（指定第二个元素排序）
def takeSecond(item):
    """
    获取列表的第二个元素
    """
    return item[1]

>>> lt.sort(key=takeSecond)
>>> print(lt)
[('c', 1), ('a', 3), ('d', 5), ('b', 10), ('e', 16)]


# 使用 lambda 表达式（指定第二个元素倒序排序）
>>> lt.sort(key=lambda x:x[1],reverse=True)
>>> print(lt)
[('e', 16), ('b', 10), ('d', 5), ('a', 3), ('c', 1)]

>>> l = ['Google', 'Baidu', 'Safari']

>>> l.clear()

>>> l 
[]

>>> l = ['Google', 'Baidu', 'Safari']

>>> l2 = l.copy()

>>> l2 
['Google', 'Baidu', 'Safari']

# 创建空元祖

tup1 = ();


# 创建只有一个元素的元祖

tup2 = (50,)


# 创建多个元素的元祖

tup3 = ('Google', 'Baidu', 'Safari')

>>> tup1 = ('Google', 'Baidu', 'Safari')

>>> tup2 = (1, 3, 5, 6)

>>> tup1[0]
'Google'

>>> tup2[1:3]
(3, 5)

>>> tup1 = (12, 34.56)

>>> tup2 = ('abc', 'xyz')


# 创建一个新的元组

>>> tup3 = tup1 + tup2

>>> tup3
(12, 34.56, 'abc', 'xyz')


# 以下修改元组元素操作是非法的

>>> tup1[0] = 100
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'tuple' object does not support item assignment

>>> tup = ('Google', 'Baidu', 'Safari')

>>> del(tup)

>>> tup 
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'tup' is not defined

>>> tup = ('Google', 'Baidu', 'Safari')

>>> tup[2]
'Safari'

>>> tup[-2]
'Baidu'

>>> tup[1:]
('Baidu', 'Safari')

>>> tup = ('Google', 'Baidu', 'Safari')

>>> len(tup)
3

>>> tup = ('Google', 'Baidu', 'Safari')

>>> max(tup)
'Safari'

>>> tup = ('Google', 'Baidu', 'Safari')

>>> min(tup)
'Baidu'

>>> l = ['Google', 'Baidu', 'Safari', 'Firefox']

>>> tup = tuple(l)

>>> tup 
('Google', 'Baidu', 'Safari', 'Firefox')

# 创建空集合

>>> set01 = {}

>>> set02 = set()

>>> print(type(set01))
<class 'dict'>

>>> print(type(set02))
<class 'set'>


# 创建多个元素的集合

basket = {'orange', 'banana', 'pear', 'apple'}

>>> netset = set(('Google', 'Baidu', 'Safari'))

>>> netset.add('Firefox')

>>> print(netset)
{'Firefox', 'Baidu', 'Google', 'Safari'}

>>> netset = set(('Google', 'Baidu', 'Safari'))

>>> netset.remove('Safari')

>>> print(netset)
{'Baidu', 'Google'}

>>> netset.remove('Firefox')   
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
KeyError: 'Firefox'

>>> netset = set(('Google', 'Baidu', 'Safari'))

>>> len(netset)
3

>>> netset = set(('Google', 'Baidu', 'Safari'))

>>> netset.clear()

>>> netset
set()

>>> netset = set(('Google', 'Baidu', 'Safari'))

>>> 'Google' in netset

>>> 'Firefox' in netset
False

>>> fruits = {'apple', 'banana', 'cherry'}

>>> fruits.add('orange') 

>>> fruits
{'banana', 'apple', 'cherry', 'orange'}


# 元素在集合中已存在

>>> fruits = {'apple', 'banana', 'cherry'}

>>> fruits.add('apple')

>>> fruits
{'banana', 'apple', 'cherry'}

>>> fruits = {'apple', 'banana', 'cherry'}

>>> fruits.clear()

>>> fruits
set()

>>> fruits = {'apple', 'banana', 'cherry'}

>>> x = fruits.copy()

>>> x
{'banana', 'apple', 'cherry'}

>>> x = {'apple', 'banana', 'cherry'}

>>> y = {'google', 'microsoft', 'apple'}

>>> z = x.difference(y) 

>>> z
{'banana', 'cherry'}

>>> x = {'apple', 'banana', 'cherry'}

>>> y = {'google', 'microsoft', 'apple'}

>>> x.difference_update(y)

>>> x 
{'banana', 'cherry'}

>>> fruits = {'apple', 'banana', 'cherry'}

>>> fruits.discard('apple')

>>> fruits
{'banana', 'cherry'}


# 移除一个不存在的元素

>>> fruits.discard('orange')

>>> x = {'apple', 'banana', 'cherry'}

>>> y = {'google', 'microsoft', 'apple'}

>>> x.intersection(y)
{'apple'}

>>> x = {'apple', 'banana', 'cherry'}

>>> y = {'google', 'microsoft', 'apple'}

>>> x.intersection_update(y)

>>> x
{'apple'}

>>> x = {'apple', 'banana', 'cherry'}

>>> y = {'google', 'microsoft', 'apple'}

>>> x.isdisjoint(y)
False

# 判断集合 x 的所有元素是否都包含在集合 y 中

>>> x = {'a', 'b', 'c'}

>>> y = {'a', 'f', 'd', 'c', 'b'}

>>> x.issubset(y)
True

# 判断集合 y 的所有元素是否都包含在集合 x 中

>>> x = {'a', 'f', 'd', 'c', 'b'}

>>> y = {'a', 'b', 'c'}

>>> x.issuperset(y)
True

>>> fruits = {'apple', 'banana', 'cherry'}

>>> fruits.pop()
'banana'

>>> fruits = {'apple', 'banana', 'cherry'}

>>> fruits.remove('apple')

>>> fruits
{'banana', 'cherry'}


# 移除一个不存在的元素

>>> fruits.remove('orange')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
KeyError: 'orange'

>>> x = {'apple', 'banana', 'cherry'}

>>> y = {'google', 'microsoft', 'apple'}

>>> x.symmetric_difference(y)
{'banana', 'microsoft', 'cherry', 'google'}

# 在原始集合 x 中移除与 y 集合中的重复元素，并将不重复的元素插入到集合 x 中

>>> x = {'apple', 'banana', 'cherry'}

>>> y = {'google', 'microsoft', 'apple'}

>>> x.symmetric_difference_update(y)

>>> x 
{'banana', 'microsoft', 'cherry', 'google'}

>>> x = {'apple', 'banana', 'cherry'}

>>> y = {'google', 'microsoft', 'apple'}

>>> x.union(y)
{'banana', 'microsoft', 'cherry', 'google', 'apple'}

>>> x = {'apple', 'banana', 'cherry'}

>>> y = {'google', 'microsoft', 'apple'}

>>> x.update(y)

>>> x 
{'banana', 'microsoft', 'cherry', 'google', 'apple'}

# 创建空字典

>>> dict1 = {}

>>> print(type(dict1))
<class 'dict'>


# 创建多个元素的字典

dict2 = {'NAME': 'Smith', 'JOB': 'Cleak', 'SALARY': '1000'}

>>> print("dict2['NAME'] =", dict2['NAME'])
dict2['NAME'] = Smith

>>> print("dict2['NO'] =", dict2['NO'])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
KeyError: 'NO'

>>> dict1 = {'NAME': 'Smith', 'JOB': 'Cleak', 'SALARY': '1000'}

# 更新字典

>>> dict1['JOB'] = 'Salesman'

>>> dict1
{'NAME': 'Smith', 'JOB': 'Salesman', 'SALARY': '1000'}


# 添加信息

>>> dict1['LOC'] = 'China'

>>> dict1 
{'NAME': 'Smith', 'JOB': 'Salesman', 'SALARY': '1000', 'LOC': 'China'}
>>> 

>>> dict1 = {'NAME': 'Smith', 'JOB': 'Cleak', 'SALARY': '1000'}


# 删除单个元素
>>> del dict1['SALARY']

>>> dict1
{'NAME': 'Smith', 'JOB': 'Cleak'}


# 清空字典

>>> dict1.clear()

>>> dict1
{}

>>> dict1 = {'NAME': 'Smith', 'JOB': 'Cleak', 'NAME': 'Blake'}

>>> dict1
{'NAME': 'Blake', 'JOB': 'Cleak'}

>>> dict1 = {['NAME']: 'Smith', 'JOB': 'Cleak', 'SALARY': '1000'}
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unhashable type: 'list'

>>> dict1 = {'NAME': 'Smith', 'JOB': 'Cleak', 'SALARY': '1000'}

>>> len(dict1)
3

>>> dict1 = {'NAME': 'Smith', 'JOB': 'Cleak', 'SALARY': '1000'}

>>> type(dict1)
<class 'dict'>

>>> dict1 = {'NAME': 'Smith', 'JOB': 'Cleak', 'SALARY': '1000'}

>>> dict1.clear()

>>> dict1
{}

>>> dict1 = {'NAME': 'Smith', 'JOB': 'Cleak', 'SALARY': '1000'}

>>> dict2 = dict1.copy()

>>> dict2 
{'NAME': 'Smith', 'JOB': 'Cleak', 'SALARY': '1000'}

>>> seq = ('name', 'age', 'sex')

>>> dict1 = dict.fromkeys(seq)

>>> dict1
{'name': None, 'age': None, 'sex': None}


>>> dict2 = dict.fromkeys(seq, 10)

>>> dict2
{'name': 10, 'age': 10, 'sex': 10}

>>> dict1 = {'NAME': 'Smith', 'JOB': 'Cleak', 'SALARY': '1000'}

>>> dict1.get('NAME')
'Smith'


# 指定的键不在字典中，返回默认值 "None"

>>> dict1.get('LOC')


# 指定的键不在字典中，自定义默认值

>>> dict1.get('LOC', "China")
'China'

>>> dict1 = {'NAME': 'Smith', 'JOB': 'Cleak', 'SALARY': '1000'}

>>> 'NAME' in dict1
True

>>> 'LOC' in dict1
False

>>> 'NAME' not in dict1
False

>>> dict1 = {'NAME': 'Smith', 'JOB': 'Cleak', 'SALARY': '1000'}

>>> dict1.items()
dict_items([('NAME', 'Smith'), ('JOB', 'Cleak'), ('SALARY', '1000')])


# 将字典的 key 和 value 变成列表

>>> dict1 = {'NAME': 'Smith', 'JOB': 'Cleak', 'SALARY': '1000'}

>>> lk = []
>>> lv = []

>>> for k, v in dict1.items():
...     lk.append(k)
...     lv.append(v)
... 

>>> print(lk)
['NAME', 'JOB', 'SALARY']

>>> print(lv)
['Smith', 'Cleak', '1000']

>>> dict1 = {'NAME': 'Smith', 'JOB': 'Cleak', 'SALARY': '1000'}

>>> dict1.keys()
dict_keys(['NAME', 'JOB', 'SALARY'])


# 转换为列表

>>> list(dict1.keys())
['NAME', 'JOB', 'SALARY']

>>> dict1 = {'NAME': 'Smith', 'JOB': 'Cleak', 'SALARY': '1000'}


# key 在字典中，返回对应的值

>>> dict1.setdefault('NAME')
'Smith'


# key 不在字典中，则插入 key 及默认值 None

>>> dict1.setdefault('LOC')

>>> dict1
{'NAME': 'Smith', 'JOB': 'Cleak', 'SALARY': '1000', 'LOC': None}


# key 不在字典中，则插入 key 及设置的默认值 SALES

>>> dict1.setdefault('DEPT', 'SALES')
'SALES'

>>> dict1
{'NAME': 'Smith', 'JOB': 'Cleak', 'SALARY': '1000', 'LOC': None, 'DEPT': 'SALES'}

>>> dict1 = {'NAME': 'Smith', 'JOB': 'Cleak', 'SALARY': '1000'}

>>> dict2 = {'LOC': 'China'}

>>> dict1.update(dict2)

>>> dict1
{'NAME': 'Smith', 'JOB': 'Cleak', 'SALARY': '1000', 'LOC': 'China'}


# 如果键值有重复，则 dict2 的内容会更新替换到 dict1 中

>>> dict1 = {'NAME': 'Smith', 'JOB': 'Cleak', 'SALARY': '1000'}

>>> dict2 = {'LOC': 'China', 'SALARY': '2000'}

>>> dict1.update(dict2)

>>> dict1
{'NAME': 'Smith', 'JOB': 'Cleak', 'SALARY': '2000', 'LOC': 'China'}

>>> fruit = {70: 'Orange', 20: 'Lemon', 50: 'Banana', 30: 'Apple'}

>>> list(fruit.values())
['Orange', 'Lemon', 'Banana', 'Apple']

>>> fruit = {70: 'Orange', 20: 'Lemon', 50: 'Banana', 30: 'Apple'}

>>> fruit.pop(20)
'Lemon'

>>> fruit
{70: 'Orange', 50: 'Banana', 30: 'Apple'}


# 如果要删除的 key 不存在，则需要添加默认值，否则会报错

>>> fruit = {70: 'Orange', 20: 'Lemon', 50: 'Banana', 30: 'Apple'}

>>> fruit.pop(100)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
KeyError: 100

>>> fruit.pop(100, 'Grape')
'Grape'

>>> fruit = {70: 'Orange', 20: 'Lemon', 50: 'Banana', 30: 'Apple'}

>>> fruit.popitem()
(30, 'Apple')

>>> fruit
{70: 'Orange', 20: 'Lemon', 50: 'Banana'}


>>> fruit.clear()

>>> fruit
{}

>>> fruit.popitem()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
KeyError: 'popitem(): dictionary is empty'

# key=operator.itemgetter(0) 表示按照 item 中的第一个字符进行排序，即按照 key 排序

>>> fruit = {70: 'Orange', 20: 'Lemon', 50: 'Banana', 30: 'Apple'}

>>> import operator

>>> sorted_key = sorted(fruit.items(), key=operator.itemgetter(0))

>>> sorted_key
[(20, 'Lemon'), (30, 'Apple'), (50, 'Banana'), (70, 'Orange')]


# key=operator.itemgetter(1) 表示按照 item 中的第二个字符进行排序，即按照 value 排序

>>> fruit = {70: 'Orange', 20: 'Lemon', 50: 'Banana', 30: 'Apple'}

>>> import operator

>>> sorted_value = sorted(fruit.items(), key=operator.itemgetter(1))

>>> sorted_value
[(30, 'Apple'), (50, 'Banana'), (20, 'Lemon'), (70, 'Orange')]

>>> print(oct(int('0b1010',2)))
0o12

>>> print(oct(int(str(0b1010))))
0o12

>>> print(int('0b1010',2))
10

>>> print(int(str(0b1010)))

>>> print(hex(int('0b1010',2)))
0xa

>>> print(hex(int(str(0b1010))))
0xa

>>> print(bin(int('0o1010',8)))
0b1000001000

>>> print(bin(int(str(0o1010))))
0b1000001000

>>> print(int('0o1010',8))
520

>>> print(int(str(0o1010)))
520

>>> print(hex(int('0o1010',8)))
0x208

>>> print(hex(int(str(0o1010))))
0x208

>>> print(bin(1010))
0b1111110010

>>> print(oct(1010))
0o1762

>>> print(hex(1010))
0x3f2

>>> print(bin(int('0x1010',16)))
0b1000000010000

>>> print(bin(int(str(0x1010))))
0b1000000010000

>>> print(oct(int('0x1010',16)))
0o10020

>>> print(oct(int(str(0x1010))))
0o10020

>>> print(int('0x1010',16))
4112

>>> print(int(str(0x1010)))
4112