python基础-内置函数详解[通俗易懂]

1 print(abs(-1))
2 print(abs(1))

1 1
2 1

1 print(all([1,2,'1']))
2 print(all([1,2,'1','']))
3 print(all(''))    #如果可迭代对象是空，就返回True

1 True
2 False
3 True

1 print(any([0,'']))
2 print(any([0,'',1]))

1 False
2 True

1 print(bin(3))

1 0b11

1 print(bool(''))  #空字符串，返回值None
2 print(bool(None))
3 print(bool(0))

1 False
2 False
3 False

1 name='你好'
2 print(bytes(name,encoding='utf-8'))  #手动把字符串编码，转成二进制
3 print(bytes(name,encoding='utf-8').decode('utf-8'))  #需要把字符串进行编码，再解码（用什么编码，就用什么解码）

1 b'\xe4\xbd\xa0\xe5\xa5\xbd'
2 你好

1 name='你好'
2 print(bytes(name,encoding='gbk'))
3 print(bytes(name,encoding='gbk').decode('gbk'))

1 b'\xc4\xe3\xba\xc3'
2 你好

1 name='你好'
2 print(bytes(name,encoding='ascii')) #ascii不能编码中文，会报错

1 Traceback (most recent call last):
2   File "D:/python/day7/built-in functions.py", line 33, in <module>
3     print(bytes(name,encoding='ascii')) #ascll不能编码中文，会报错
4 UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-1: ordinal not in range(128)

1 print(chr(46))   #ascll 码对应的编码

1 .

1 print(dir(dict))  #打印内置属性和方法

1 ['__class__', '__contains__', '__delattr__', '__delitem__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__gt__', '__hash__', '__init__', '__iter__', '__le__', '__len__', '__lt__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__setitem__', '__sizeof__', '__str__', '__subclasshook__', 'clear', 'copy', 'fromkeys', 'get', 'items', 'keys', 'pop', 'popitem', 'setdefault', 'update', 'values']

1 print(divmod(10,3))    #取商得余数，用于做分页显示

1 (3, 1)

1 dic={'name':'alex'}  #字典类型转成字符串 2 dic_str=str(dic)
3 print(dic_str)
4 
5 d1=eval(dic_str)     #eval:把字符串中的数据结构给提取出来
6 print(d1)

1 {'name': 'alex'}
2 
3 {'name': 'alex'}

 1 #hash的作用：去网上下载软件，判断是否被人修改，通过比对hash值，就知道
 2 print(hash('12sdfdsaf3123123sdfasdfasdfasdfasdfasdfasdfasdfasfasfdasdf'))
 3 print(hash('12sdfdsaf31231asdfasdfsadfsadfasdfasdf23'))
 4 
 5 name='alex'
 6 print(hash(name))
 7 print(hash(name))
 8 
 9 print('--->before',hash(name))
10 name='sb'
11 print('=-=>after',hash(name))

1 1982976672
2 864959982
3 -2006403263
4 -2006403263
5 --->before -2006403263
6 =-=>after 805524431

1 print(help(all))   #查看函数用法的详细信息

1 Help on built-in function all in module builtins:
2 
3 all(iterable, /)
4     Return True if bool(x) is True for all values x in the iterable.
5     
6     If the iterable is empty, return True.
7 
8 None

1 print(bin(10))   #10进制->2进制
2 print(hex(12))   #10进制->16进制
3 print(oct(12))   #10进制->8进制

1 0b1010     #10进制->2进制

2 0xc        #10进制->16进制

3 0o14       #10进制->8进制

1 print(isinstance(1,int))       #判断是不是int类型
2 print(isinstance('abc',str))   #判断字符串
3 print(isinstance([],list))     #判断列表
4 print(isinstance({},dict))     #判断字典
5 print(isinstance({1,2},set))   #判断集合

1 True
2 True
3 True
4 True
5 True

1 name='哈哈哈哈哈哈哈哈哈哈哈哈哈哈啊哈粥少陈'
2 print(globals())   #全局变量

1 {'__doc__': None, '__name__': '__main__', '__loader__': <_frozen_importlib_external.SourceFileLoader object at 0x01625C30>, '__cached__': None, 'name': '哈哈哈哈哈哈哈哈哈哈哈哈哈哈啊哈粥少陈', '__package__': None, '__builtins__': <module 'builtins' (built-in)>, '__spec__': None, '__file__': 'D:/python/day7/built-in functions.py'}

1 name='哈哈哈哈哈哈哈哈哈哈哈哈哈哈啊哈粥少陈'
2 print(__file__)    #直接打印文件名

1 D:/python/day7/built-in functions.py

1 def test():
2     age='1111111111111111111111111111111111111111111111111111111111111'
3     print(globals())   #打印全局变量
4     print(locals())    #打印上一层的变量
5 
6 test()

1 {'__builtins__': <module 'builtins' (built-in)>, '__loader__': <_frozen_importlib_external.SourceFileLoader object at 0x01CD5C30>, '__file__': 'D:/python/day7/built-in functions.py', 'test': <function test at 0x01DE2F60>, '__package__': None, '__cached__': None, '__name__': '__main__', '__spec__': None, '__doc__': None}
2 {'age': '1111111111111111111111111111111111111111111111111111111111111'}

1 l=[1,3,100,-1,2]
2 print(max(l))
3 print(min(l))

1 100  #最大值
2 -1     #最小值

1 age_dic={'alex_age':18,'wupei_age':20,'zsc_age':100,'lhf_age':30}
2 print(max(age_dic.values()))   #取出最大年龄
3 print(max(age_dic))            #默认比较的是字典的key

1 100
2 zsc_age

1 age_dic={'alex_age':18,'wupei_age':20,'zsc_age':100,'lhf_age':30}
2 for item in zip(age_dic.values(),age_dic.keys()):  #[(18,'alex_age')  (20,'wupeiqi_age') () () ()]
3     print(item)
4 
5 #取出年龄最大的key和values
6 print('=======>',list(max(zip(age_dic.values(),age_dic.keys()))))  #max和zip联合使用

1 (100, 'zsc_age')
2 (30, 'lhf_age')
3 (18, 'alex_age')
4 (20, 'wupei_age')
5 
6 
7 =======> [100, 'zsc_age']  #取出年龄最大的key和values

 1 l=[
 2     (5,'e'),
 3     (1,'b'),
 4     (3,'a'),
 5     (4,'d'),
 6 ]
 7 l1=['a10','b12','c10',100]   #不同类型之间不能进行比较
 8 l1=['a10','a2','a10']        #不同类型之间不能进行比较
 9 print(list(max(l)))
10 
11 print('--->',list(max(l1)))

1 [5, 'e']
2 ---> ['a', '2']

1 print(list(zip(('a','n','c'),(1,2,3))))
2 print(list(zip(('a','n','c'),(1,2,3,4))))
3 print(list(zip(('a','n','c','d'),(1,2,3))))

1 [('a', 1), ('n', 2), ('c', 3)]
2 [('a', 1), ('n', 2), ('c', 3)]
3 [('a', 1), ('n', 2), ('c', 3)]

1 p={'name':'alex','age':18,'gender':'none'}
2 print(list(zip(p.keys(),p.values())))
3 print(list(p.keys()))    #取keys
4 print(list(p.values()))  #values
5 
6 print(list(zip(['a','b'],'12345')))   #列表，只要是序列就可以打印出来

1 [('age', 18), ('name', 'alex'), ('gender', 'none')]
2 ['age', 'name', 'gender']
3 [18, 'alex', 'none']
4 [('a', '1'), ('b', '2')]

 1 l=[1,3,100,-1,2]
 2 print(max(l))    #比较出最大值
 3 
 4 
 5 dic={'age1':18,'age2':10}
 6 print(max(dic))           #比较的是key
 7 
 8 
 9 print(max(dic.values()))  #比较的是key，但是不知道是那个key对应的值
10 
11 
12 print(max(zip(dic.values(),dic.keys())))   #结合zip使用

1 100    #比较大小，得出最大值   
2 
3 age2   #比较的是key
4 
5 18     #比较的是key,但是不知道是那个key对应的值
6 
7 (18, 'age1')   #结合zip拿用

 1 people=[
 2     {'name':'alex','age':1000},
 3     {'name':'wupei','age':10000},
 4     {'name':'yuanhao','age':9000},
 5     {'name':'linhaifeng','age':18},
 6 ]
 7 # max(people,key=lambda dic:dic['age'])
 8 print('周绍陈取出来没有',max(people,key=lambda dic:dic['age']))    #提取年龄中的values,再进行比较
 9 
10 #上面题分解步骤，先取出ret的值，再给max进行比较
11 people=[
12     {'name':'alex','age':1000},
13     {'name':'wupei','age':10000},
14     {'name':'yuanhao','age':9000},
15     {'name':'linhaifeng','age':18},
16 ]
17 
18 ret=[]
19 for item in people:
20     ret.append(item['age'])
21 print(ret)
22 max(ret)

1 #提取年龄中的values,再进行比较大小，得出age最大的
2 
3 周绍陈取出来没有 {'name': 'wupei', 'age': 10000}
4 
5 
6 #上面题分解步骤，先取出ret的值，再给max进行比较，得出的值：
7 
8 [1000, 10000, 9000, 18]

1 print(chr(97))     #ascll码应对的编码
2 
3 print(ord('a'))    #ascll码应对的数字
4 
5 print(pow(3,3))    #3**3   几的几次方，相当于3的3次方
6 
7 print(pow(3,3,2))  #3**3%2    3的3次方，取余

1 a       #ascll码应对的编码
2 
3 97     #ascll码应对的数字
4 
5 27     #3**3   几的几次方，相当于3的3次方
6  
7 1       #3**3%2    3的3次方，取余

1 l=[1,2,3,4]
2 print(list(reversed(l)))
3 print(l)

1 [4, 3, 2, 1]   #反转
2 [1, 2, 3, 4]

1 print(round(3.5))   #四舍五入

1 4

1 print(set('hello'))   #集合

1 {'l', 'e', 'o', 'h'}

 1 l='hello'
 2 s1=slice(3,5)    #切片 取3到5的元素
 3 s2=slice(1,4,2)  #切片，指定步长为2
 4 print(l[3:5])
 5 
 6 print(l[s1])   #切片
 7 print(l[s2])
 8 
 9 print(s2.start)  #开始
10 print(s2.stop)   #结束
11 print(s2.step)   步长

 1 lo
 2 
 3 lo
 4 
 5 el
 6 
 7 1
 8 
 9 4
10 
11 2

1 l=[3,2,1,5,7]
2 l1=[3,2,'a',1,5,7]
3 print(sorted(l))    #排序
4 # print(sorted(l1)) #直接运行会报错，因为排序本质就是在比较大小，不同类型之间不可以比较大小

1 [1, 2, 3, 5, 7]

1 people=[
2     {'name':'alex','age':1000},
3     {'name':'wupei','age':10000},
4     {'name':'yuanhao','age':9000},
5     {'name':'linhaifeng','age':18},
6 ]
7 print(sorted(people,key=lambda dic:dic['age']))    #按年龄进行排序

1 [{'age': 18, 'name': 'linhaifeng'}, {'age': 1000, 'name': 'alex'}, {'age': 9000, 'name': 'yuanhao'}, {'age': 10000, 'name': 'wupei'}]

 1 name_dic={
 2     'abyuanhao': 11900,
 3     'alex':1200,
 4     'wupei':300,
 5 }
 6 print(sorted(name_dic))   #按key排序
 7 
 8 print(sorted(name_dic,key=lambda key:name_dic[key]))   #取出字典的values
 9 
10 print(sorted(zip(name_dic.values(),name_dic.keys())))   #按价格从低到高排序

1 ['abyuanhao', 'alex', 'wupei']
2 
3 ['wupei', 'alex', 'abyuanhao']
4 
5 [(300, 'wupei'), (1200, 'alex'), (11900, 'abyuanhao')]

1 print(str('1'))             #str  转换成字符型
2 print(type(str({'a':1})))   #type 查看数据类型
3 
4 dic_str=str({'a':1})
5 print(type(eval(dic_str)))  #eval 转换数据类型

1 1
2 <class 'str'>
3 <class 'dict'>

1 msg='123'
2 if type(msg) is str:
3     msg=int(msg)
4     res=msg+1
5     print(res)

1 124

1 def test():
2     msg='撒旦法阿萨德防撒旦浪费艾丝凡阿斯蒂芬'
3     print(locals())    #打印出上一层的值，如果上一层没有，再往上找
4     print(vars())      #如果没有参数，跟locals一样，如果有参数，查看某一个方法，显示成字典的方式
5 test()
6 print(vars(int))   

1 {'msg': '撒旦法阿萨德防撒旦浪费艾丝凡阿斯蒂芬'}
2 {'msg': '撒旦法阿萨德防撒旦浪费艾丝凡阿斯蒂芬'}
3 {'denominator': <attribute 'denominator' of 'int' objects>, '__mod__': <slot wrapper '__mod__' of 'int' objects>, '__radd__': <slot wrapper '__radd__' of 'int' objects>, '__floordiv__': <slot wrapper '__floordiv__' of 'int' objects>, '__doc__': "int(x=0) -> integer\nint(x, base=10) -> integer\n\nConvert a number or string to an integer, or return 0 if no arguments\nare given.  If x is a number, return x.__int__().  For floating point\nnumbers, this truncates towards zero.\n\nIf x is not a number or if base is given, then x must be a string,\nbytes, or bytearray instance representing an integer literal in the\ngiven base.  The literal can be preceded by '+' or '-' and be surrounded\nby whitespace.  The base defaults to 10.  Valid bases are 0 and 2-36.\nBase 0 means to interpret the base from the string as an integer literal.\n>>> int('0b100', base=0)\n4", '__ceil__': <method '__ceil__' of 'int' objects>, '__sizeof__': <method '__sizeof__' of 'int' objects>, '__pos__': <slot wrapper '__pos__' of 'int' objects>, '__gt__': <slot wrapper '__gt__' of 'int' objects>, '__rtruediv__': <slot wrapper '__rtruediv__' of 'int' objects>, '__sub__': <slot wrapper '__sub__' of 'int' objects>, '__rdivmod__': <slot wrapper '__rdivmod__' of 'int' objects>, '__new__': <built-in method __new__ of type object at 0x5D677028>, '__rshift__': <slot wrapper '__rshift__' of 'int' objects>, '__rmod__': <slot wrapper '__rmod__' of 'int' objects>, '__neg__': <slot wrapper '__neg__' of 'int' objects>, '__xor__': <slot wrapper '__xor__' of 'int' objects>, '__rmul__': <slot wrapper '__rmul__' of 'int' objects>, '__repr__': <slot wrapper '__repr__' of 'int' objects>, '__hash__': <slot wrapper '__hash__' of 'int' objects>, 'to_bytes': <method 'to_bytes' of 'int' objects>, 'from_bytes': <method 'from_bytes' of 'int' objects>, 'real': <attribute 'real' of 'int' objects>, '__lt__': <slot wrapper '__lt__' of 'int' objects>, '__invert__': <slot wrapper '__invert__' of 'int' objects>, '__eq__': <slot wrapper '__eq__' of 'int' objects>, '__float__': <slot wrapper '__float__' of 'int' objects>, '__round__': <method '__round__' of 'int' objects>, '__ror__': <slot wrapper '__ror__' of 'int' objects>, '__le__': <slot wrapper '__le__' of 'int' objects>, '__rlshift__': <slot wrapper '__rlshift__' of 'int' objects>, 'bit_length': <method 'bit_length' of 'int' objects>, '__getnewargs__': <method '__getnewargs__' of 'int' objects>, '__index__': <slot wrapper '__index__' of 'int' objects>, '__rsub__': <slot wrapper '__rsub__' of 'int' objects>, '__format__': <method '__format__' of 'int' objects>, '__bool__': <slot wrapper '__bool__' of 'int' objects>, '__or__': <slot wrapper '__or__' of 'int' objects>, '__int__': <slot wrapper '__int__' of 'int' objects>, 'imag': <attribute 'imag' of 'int' objects>, 'conjugate': <method 'conjugate' of 'int' objects>, '__ge__': <slot wrapper '__ge__' of 'int' objects>, '__and__': <slot wrapper '__and__' of 'int' objects>, '__abs__': <slot wrapper '__abs__' of 'int' objects>, '__floor__': <method '__floor__' of 'int' objects>, '__divmod__': <slot wrapper '__divmod__' of 'int' objects>, '__trunc__': <method '__trunc__' of 'int' objects>, '__rrshift__': <slot wrapper '__rrshift__' of 'int' objects>, '__mul__': <slot wrapper '__mul__' of 'int' objects>, '__pow__': <slot wrapper '__pow__' of 'int' objects>, '__str__': <slot wrapper '__str__' of 'int' objects>, '__ne__': <slot wrapper '__ne__' of 'int' objects>, '__getattribute__': <slot wrapper '__getattribute__' of 'int' objects>, '__truediv__': <slot wrapper '__truediv__' of 'int' objects>, '__add__': <slot wrapper '__add__' of 'int' objects>, '__rand__': <slot wrapper '__rand__' of 'int' objects>, '__rfloordiv__': <slot wrapper '__rfloordiv__' of 'int' objects>, '__lshift__': <slot wrapper '__lshift__' of 'int' objects>, '__rxor__': <slot wrapper '__rxor__' of 'int' objects>, 'numerator': <attribute 'numerator' of 'int' objects>, '__rpow__': <slot wrapper '__rpow__' of 'int' objects>}

1 def say_hi():
2     print('你好啊林师傅')

1 import test     #导入一个模块，模块就是一个py文件
2 test.say_hi()

1 你好啊林师傅

1 def say_hi():
2     print('你好啊林师傅')

1 module_name='test'
2 m=__import__(module_name)   #有字符串的模块
3 m.say_hi()

1 你好啊林师傅