python数据类型之内置方法

2021-06-27 11:06

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标签：pytho table get 插入判断 ima result dba 很多

python有六大数据类型，分别为整型、字符串、列表、字典、元祖和集合，这些基本数据类型都内置了很多方法，接下来一一探寻。

一整型

python中整型有两种：int和float

1 int

使用dir函数查看有多少内置方法

# python3.x
dir(int)
# [‘__abs__‘, ‘__add__‘, ‘__and__‘, ‘__bool__‘, ‘__ceil__‘, ‘__class__‘, ‘__delattr__‘, ‘__dir__‘, ‘__divmod__‘, ‘__doc__‘, 
‘__eq__‘, ‘__float__‘, ‘__floor__‘, ‘__floordiv__‘, ‘__format__‘, ‘__ge__‘, ‘__getattribute__‘, ‘__getnewargs__‘, ‘__gt__‘, 
‘__hash__‘, ‘__index__‘, ‘__init__‘, ‘__int__‘, ‘__invert__‘, ‘__le__‘, ‘__lshift__‘, ‘__lt__‘, ‘__mod__‘, ‘__mul__‘, ‘__ne__‘, 
‘__neg__‘, ‘__new__‘, ‘__or__‘, ‘__pos__‘, ‘__pow__‘, ‘__radd__‘, ‘__rand__‘, ‘__rdivmod__‘, ‘__reduce__‘, ‘__reduce_ex__‘, 
‘__repr__‘, ‘__rfloordiv__‘, ‘__rlshift__‘, ‘__rmod__‘, ‘__rmul__‘, ‘__ror__‘, ‘__round__‘, ‘__rpow__‘, ‘__rrshift__‘, ‘__rshift__‘, 
‘__rsub__‘, ‘__rtruediv__‘, ‘__rxor__‘, ‘__setattr__‘, ‘__sizeof__‘, ‘__str__‘, ‘__sub__‘, ‘__subclasshook__‘, ‘__truediv__‘, ‘__trunc__‘, 
‘__xor__‘, ‘bit_length‘, ‘conjugate‘, ‘denominator‘, ‘from_bytes‘, ‘imag‘, ‘numerator‘, ‘real‘, ‘to_bytes‘]


# python 2.x
dir(int)
# [‘__abs__‘, ‘__add__‘, ‘__and__‘, ‘__class__‘, ‘__cmp__‘, ‘__coerce__‘, ‘__delattr__‘, ‘__div__‘, ‘__divmod__‘, ‘__doc__‘, 
‘__float__‘, ‘__floordiv__‘, ‘__format__‘, ‘__getattribute__‘, ‘__getnewargs__‘, ‘__hash__‘, ‘__hex__‘, ‘__index__‘, ‘__init__‘, 
‘__int__‘, ‘__invert__‘, ‘__long__‘, ‘__lshift__‘, ‘__mod__‘, ‘__mul__‘, ‘__neg__‘, ‘__new__‘, ‘__nonzero__‘, ‘__oct__‘, ‘__or__‘, 
‘__pos__‘, ‘__pow__‘, ‘__radd__‘, ‘__rand__‘, ‘__rdiv__‘, ‘__rdivmod__‘, ‘__reduce__‘, ‘__reduce_ex__‘, ‘__repr__‘, ‘__rfloordiv__‘, 
‘__rlshift__‘, ‘__rmod__‘, ‘__rmul__‘, ‘__ror__‘, ‘__rpow__‘, ‘__rrshift__‘, ‘__rshift__‘, ‘__rsub__‘, ‘__rtruediv__‘, ‘__rxor__‘, 
‘__setattr__‘, ‘__sizeof__‘, ‘__str__‘, ‘__sub__‘, ‘__subclasshook__‘, ‘__truediv__‘, ‘__trunc__‘, ‘__xor__‘, ‘bit_length‘, ‘conjugate‘, 
‘denominator‘, ‘imag‘, ‘numerator‘, ‘real‘]

因为是整型类型，所以有加减乘除、取绝对值的方法，像__abs__是取绝对值，__add__是加法等，其中重要的几个方法是：bit_length、conjugate、from_bytes、imag、numerator、real、to_bytes

digit = 123
print(digit.bit_length())
# 进入源码，Number of bits necessary to represent self in binary
# 首先把int型转为二进制，然后计算二进制的位数

bit_length

num = 2.3 - 2.5j
result = num.real       #复数的实部
print(result)   #打印输出2.3
result = num.imag    #复数的虚部
print(result)   #打印输出2.5j

result = num.conjugate()   #返回该复数的共轭复数
print(result)  #打印输出(2.3+2.5j)

conjugate

print(int.from_bytes(bytes=b‘A‘, byteorder=‘little‘)
 
 
#打印输出 65  ，即将字符A转换为十进制

from_bytes

num = 2
result = num.to_bytes(5,byteorder=‘little‘)
print(result)
#打印输出b‘\x02\x00\x00\x00\x00‘
for i in result:
    print(i)


#打印输出2\n0\n0\n0\n0
#\n表示回车

to_bytes

imag、real分别是计算出复制的实部和虚部，conjugate得出共轭复数，numerator不知道什么鬼。

2 str

#python3.5
dir(str)
#[‘__add__‘, ‘__class__‘, ‘__contains__‘, ‘__delattr__‘, ‘__dir__‘, ‘__doc__‘, ‘__eq__‘, ‘__format__‘, ‘__ge__‘, ‘__getattribute__‘, 
‘__getitem__‘, ‘__getnewargs__‘, ‘__gt__‘, ‘__hash__‘, ‘__init__‘, ‘__iter__‘, ‘__le__‘, ‘__len__‘, ‘__lt__‘, ‘__mod__‘, ‘__mul__‘, 
‘__ne__‘, ‘__new__‘, ‘__reduce__‘, ‘__reduce_ex__‘, ‘__repr__‘, ‘__rmod__‘, ‘__rmul__‘, ‘__setattr__‘, ‘__sizeof__‘, ‘__str__‘, 
‘__subclasshook__‘, ‘capitalize‘, ‘casefold‘, ‘center‘, ‘count‘, ‘encode‘, ‘endswith‘, ‘expandtabs‘, ‘find‘, ‘format‘, ‘format_map‘, 
‘index‘, ‘isalnum‘, ‘isalpha‘, ‘isdecimal‘, ‘isdigit‘, ‘isidentifier‘, ‘islower‘, ‘isnumeric‘, ‘isprintable‘, ‘isspace‘, ‘istitle‘, ‘isupper‘, 
‘join‘, ‘ljust‘, ‘lower‘, ‘lstrip‘, ‘maketrans‘, ‘partition‘, ‘replace‘, ‘rfind‘, ‘rindex‘, ‘rjust‘, ‘rpartition‘, ‘rsplit‘, ‘rstrip‘, 
‘split‘, ‘splitlines‘, ‘startswith‘, ‘strip‘, ‘swapcase‘, ‘title‘, ‘translate‘, ‘upper‘, ‘zfill‘]

#python2.7
dir(str)
#[‘__add__‘, ‘__class__‘, ‘__contains__‘, ‘__delattr__‘, ‘__doc__‘, ‘__eq__‘, ‘__format__‘, ‘__ge__‘, ‘__getattribute__‘, ‘__getitem__‘, 
‘__getnewargs__‘, ‘__getslice__‘, ‘__gt__‘, ‘__hash__‘, ‘__init__‘, ‘__le__‘, ‘__len__‘, ‘__lt__‘, ‘__mod__‘, ‘__mul__‘, ‘__ne__‘, ‘__new__‘, 
‘__reduce__‘, ‘__reduce_ex__‘, ‘__repr__‘, ‘__rmod__‘, ‘__rmul__‘, ‘__setattr__‘, ‘__sizeof__‘, ‘__str__‘, ‘__subclasshook__‘, 
‘_formatter_field_name_split‘, ‘_formatter_parser‘, ‘capitalize‘, ‘center‘, ‘count‘, ‘decode‘, ‘encode‘, ‘endswith‘, ‘expandtabs‘, 
‘find‘, ‘format‘, ‘index‘, ‘isalnum‘, ‘isalpha‘, ‘isdigit‘, ‘islower‘, ‘isspace‘, ‘istitle‘, ‘isupper‘, ‘join‘, ‘ljust‘, ‘lower‘, ‘lstrip‘, 
‘partition‘, ‘replace‘, ‘rfind‘, ‘rindex‘, ‘rjust‘, ‘rpartition‘, ‘rsplit‘, ‘rstrip‘, ‘split‘, ‘splitlines‘, ‘startswith‘, ‘strip‘, 
‘swapcase‘, ‘title‘, ‘translate‘, ‘upper‘, ‘zfill‘]

# 计算字符串中某个字符的总数
str1 = ‘aaabc‘
print(str1.count(‘a‘))
# 输出结果为 3

count

capitalize

# 编码 默认为utf-8(Unicode)
str1 = ‘aaabc‘
print(str1.encode())
# 输出结果为 b‘aaabc‘

encode

# 判断字符串是否已某个字符结束，返回值为布尔值
str1 = ‘aaabc‘
print(str1.endswith(‘c‘))
# 输出结果为 True

endswitch

# 找到字符串中某个字符第一次出现的索引
str1 = ‘aaabc‘
print(str1.find(‘a‘))
# 输出结果为 0

find

# 返回某个字符第一次出现的索引
str1 = ‘aaabc‘
print(str1.index(‘a‘))
# 输出结果为 0

index

# 判断字符串中字符是否都是数字，返回一个布尔值
str1 = ‘aaabc‘
print(str1.isdigit())
# 输出结果为 False

str2 = ‘123‘
print(str2.isdigit())
# 输出结果为 True

isdigit

# 判断字符串中的字符是否全为小写
S = ‘abc‘
print(S.islower())
# 输出结果为True

S = ‘123‘
print(S.islower())
# 输出结果为False

islower

# 判断S中字符是否全为大写
S = ‘ABC‘
print(S.isupper())
# 输出结果为True

S = ‘123‘
print(S.isupper())
# 输出结果为False

isupper

# 将S中的字符用分隔符分隔
S = ‘abcd‘
print(‘.‘.join(S))
# 输出结果为 a.b.c.d

join

# 将S中的字符全改为小写
S = ‘AbCd123‘
print(S.lower())
# 输出结果为 abcd123

lower

# 将S中左边的空格去掉
S = ‘  AbCd123‘
print(S.lstrip())
# 输出结果为 AbCd123

lstrip

# 将S中的字符用字符替换
S = ‘AbCd123‘
print(S.replace(‘A‘, ‘a‘))
# 输出结果为 abCd123

replace

S = ‘AbCd123‘
print(S.split(‘d‘))
# 输出结果为 [‘AbC‘, ‘123‘]

split

# 判断S是否以某个字符开始，返回一个布尔值
S = ‘AbCd123‘
print(S.startswith(‘A‘))
# 输出结果为 True

S = ‘AbCd123‘
print(S.startswith(‘d‘))
# 输出结果为 False

startswitch

# 将S左右两边的空格去掉
S = ‘  AbCd123   ‘
print(S.strip())
# 输出结果为 AbCd123

strip

# 将S中所有的字符大写
S = ‘AbCd123   ‘
print(S.upper())
# 输出结果为 ABCD123

upper

3 list

# python 3.x
dir(list)
# [‘__add__‘, ‘__class__‘, ‘__contains__‘, ‘__delattr__‘, ‘__delitem__‘, ‘__dir__‘, ‘__doc__‘, ‘__eq__‘, ‘__format__‘, ‘__ge__‘, 
‘__getattribute__‘, ‘__getitem__‘, ‘__gt__‘, ‘__hash__‘, ‘__iadd__‘, ‘__imul__‘, ‘__init__‘, ‘__iter__‘, ‘__le__‘, ‘__len__‘, ‘__lt__‘, 
‘__mul__‘, ‘__ne__‘, ‘__new__‘, ‘__reduce__‘, ‘__reduce_ex__‘, ‘__repr__‘, ‘__reversed__‘, ‘__rmul__‘, ‘__setattr__‘, ‘__setitem__‘, 
‘__sizeof__‘, ‘__str__‘, ‘__subclasshook__‘, ‘append‘, ‘clear‘, ‘copy‘, ‘count‘, ‘extend‘, ‘index‘, ‘insert‘, ‘pop‘, ‘remove‘, 
‘reverse‘, ‘sort‘]

# python 2.x
dir(list)
# [‘__add__‘, ‘__class__‘, ‘__contains__‘, ‘__delattr__‘, ‘__delitem__‘, ‘__delslice__‘, ‘__doc__‘, ‘__eq__‘, ‘__format__‘, ‘__ge__‘, 
‘__getattribute__‘, ‘__getitem__‘, ‘__getslice__‘, ‘__gt__‘, ‘__hash__‘, ‘__iadd__‘, ‘__imul__‘, ‘__init__‘, ‘__iter__‘, ‘__le__‘, ‘__len__‘, 
‘__lt__‘, ‘__mul__‘, ‘__ne__‘, ‘__new__‘, ‘__reduce__‘, ‘__reduce_ex__‘, ‘__repr__‘, ‘__reversed__‘, ‘__rmul__‘, ‘__setattr__‘, ‘__setitem__‘, 
‘__setslice__‘, ‘__sizeof__‘, ‘__str__‘, ‘__subclasshook__‘, ‘append‘, ‘count‘, ‘extend‘, ‘index‘, ‘insert‘, ‘pop‘, ‘remove‘, ‘reverse‘, ‘sort‘]

# 往列表追加元素
lis = [‘a‘, ‘b‘, ‘c‘, 1, 2, 3]
lis.append(4)
print(lis)
# 输出结果 [‘a‘, ‘b‘, ‘c‘, 1, 2, 3, 4]

append

# 清空列表
lis = [‘a‘, ‘b‘, ‘c‘, 1, 2, 3]
lis.clear()
print(lis)
# 输出结果 []

clear

# 拷贝一个列表并返回该列表
lis = [‘a‘, ‘b‘, ‘c‘, 1, 2, 3]
lis1 = lis.copy()
print(lis1)
# 输出结果 [‘a‘, ‘b‘, ‘c‘, 1, 2, 3]

copy

# 计算列表中某个元素的数量
lis = [‘a‘, ‘b‘, ‘c‘, 1, 2, 3]
lis1 = lis.copy()
print(lis1)
# 输出结果 [‘a‘, ‘b‘, ‘c‘, 1, 2, 3]

count

# 合并列表
lis1 = [‘a‘, ‘b‘, ‘c‘, 1, 2, 3]
lis2 = [4, 5, 6, 7, 8]
lis1.extend(lis2)
print(lis1)
# 输出结果 [‘a‘, ‘b‘, ‘c‘, 1, 2, 3, 4, 5, 6, 7, 8]

extend

# 返回列表中元素的第一个出现位置的索引
lis1 = [‘a‘, ‘a‘, ‘b‘, ‘c‘, 1, 2, 3]
ind = lis1.index(‘a‘)
print(ind)
# 输出结果 0

index

# 插入到列表中某个索引位置
lis1 = [‘a‘, ‘a‘, ‘b‘, ‘c‘, 1, 2, 3]
lis1.insert(4, ‘d‘)
print(lis1)
# 输出结果 [‘a‘, ‘a‘, ‘b‘, ‘c‘, ‘d‘, 1, 2, 3]

insert

# 弹出列表中某个索引位置的值，默认弹出最后一个
lis1 = [‘a‘, ‘a‘, ‘b‘, ‘c‘, 1, 2, 3]
lis1.pop()
print(lis1)
# 输出结果 [‘a‘, ‘a‘, ‘b‘, ‘c‘, ‘d‘, 1, 2, ]

lis1 = [‘a‘, ‘a‘, ‘b‘, ‘c‘, 1, 2, 3]
lis1.pop(4)
print(lis1)
# 输出结果 [‘a‘, ‘a‘, ‘b‘, ‘c‘, ‘d‘, 2, 3]

pop

# 删除列表中的元素
lis1 = [‘a‘, ‘a‘, ‘b‘, ‘c‘, 1, 2, 3]
a = lis1.remove(‘a‘)
print(lis1)
# 输出结果 [‘a‘, ‘b‘, ‘c‘, 1, 2, 3]
# 和pop方法不同的地方有两个：pop通过索引取出值，有返回值；remove通过元素删除，没有返回值

remove

# 反转列表
lis1 = [‘a‘, ‘a‘, ‘b‘, ‘c‘, 1, 2, 3]
lis1.reverse()
print(lis1)
# 输出结果 [3, 2, 1, ‘c‘, ‘b‘, ‘a‘, ‘a‘]

reverse

# 排序
lis1 = [‘a‘, ‘a‘, ‘b‘, ‘c‘, ‘r‘, ‘c‘, ‘g‘, ‘l‘]
lis1.sort()
print(lis1)
# 输出结果 [‘a‘, ‘a‘, ‘b‘, ‘c‘, ‘c‘, ‘g‘, ‘l‘, ‘r‘]

sort

4 dict

#python3.x
dir(dict)
#[‘__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‘]

#python2.x
dir(dict)
#[‘__class__‘, ‘__cmp__‘, ‘__contains__‘, ‘__delattr__‘, ‘__delitem__‘, ‘__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‘, ‘has_key‘, ‘items‘, 
‘iteritems‘, ‘iterkeys‘, ‘itervalues‘, ‘keys‘, ‘pop‘, ‘popitem‘, ‘setdefault‘, ‘update‘, ‘values‘, ‘viewitems‘, ‘viewkeys‘, ‘viewvalues‘]

# 清空字典
dic = {‘name‘: ‘szz‘, ‘age‘: ‘18‘, ‘addr‘: ‘shanghai‘}
dic.clear()
print(dic)
# 输出结果 {}

clear

# 拷贝字典
dic = {‘name‘: ‘szz‘, ‘age‘: ‘18‘, ‘addr‘: ‘shanghai‘}
dic1 = dic.copy()
print(dic1)
# 输出结果 {‘name‘: ‘szz‘, ‘age‘: ‘18‘, ‘addr‘: ‘shanghai‘}

copy

# 返回一个新的字典
dic = {‘name‘: ‘szz‘, ‘age‘: ‘18‘, ‘addr‘: ‘shanghai‘}
dic1 = dic.fromkeys((‘l‘), (‘hashangda‘))
print(dic1)
print(dic)
# 输出结果 [‘l‘: ‘hashangda‘}
# {‘name‘: ‘szz‘, ‘age‘: ‘18‘, ‘addr‘: ‘shanghai‘}
# 不改变前面的字典

fromkeys

# 通过key取值，如果取不到也不报错
dic = {‘name‘: ‘szz‘, ‘age‘: ‘18‘, ‘addr‘: ‘shanghai‘}
name1 = dic.get(‘name‘)
other = dic.get(‘school‘)
print(name1)
print(other)
# 输出结果 szz，None

get

# 获取字典的key和value
dic = {‘name‘: ‘szz‘, ‘age‘: ‘18‘, ‘addr‘: ‘shanghai‘}
for key, value in dic.items():
    print(key, value)
# 输出结果 name szz age 18 addr shanghai

items

# 获取字典所有的键值
dic = {‘name‘: ‘szz‘, ‘age‘: ‘18‘, ‘addr‘: ‘shanghai‘}
keys = dic.keys()
print(keys)
# 输出结果 dict_keys([‘name‘, ‘age‘, ‘addr‘])

keys

# 弹出字典中的键值对
dic = {‘name‘: ‘szz‘, ‘age‘: ‘18‘, ‘addr‘: ‘shanghai‘, ‘school‘: ‘hashangda‘}
item = dic.pop(‘name‘)
print(item)
print(dic)
# 输出结果 szz {‘age‘: ‘18‘, ‘addr‘: ‘shanghai‘, ‘school‘: ‘hashangda‘}

pop

# 弹出字典中最后一个键值对
dic = {‘name‘: ‘szz‘, ‘age‘: ‘18‘, ‘addr‘: ‘shanghai‘, ‘school‘: ‘hashangda‘}
item = dic.popitem()
print(item)
print(dic)
# 输出结果 (‘school‘, ‘hashangda‘) {‘name‘: ‘szz‘, ‘age‘: ‘18‘, ‘addr‘: ‘shanghai‘}
# 弹出的键和值用列表存储

popitem

# 给字典设置默认值
dic = {‘name‘: ‘szz‘, ‘age‘: ‘18‘, ‘addr‘: ‘shanghai‘, ‘school‘: ‘hashangda‘}
dic.setdefault(‘male‘, 1)
print(dic)
# 输出结果 {‘name‘: ‘szz‘, ‘age‘: ‘18‘, ‘addr‘: ‘shanghai‘, ‘school‘: ‘hashangda‘, ‘male‘: 1}

setdeafault

# 更新字典中的键值对
dic = {‘name‘: ‘szz‘, ‘age‘: ‘18‘, ‘addr‘: ‘shanghai‘, ‘school‘: ‘hashangda‘}
dic1 = {‘age‘: 23}
dic.update(dic1)
print(dic)
# 输出结果 {‘name‘: ‘szz‘, ‘age‘: 23, ‘addr‘: ‘shanghai‘, ‘school‘: ‘hashangda‘}

update

# 得到字典所有的值
dic = {‘name‘: ‘szz‘, ‘age‘: ‘18‘, ‘addr‘: ‘shanghai‘, ‘school‘: ‘hashangda‘}
values = dic.values()
print(values)
# 输出结果 dict_values([‘szz‘, ‘18‘, ‘shanghai‘, ‘hashangda‘])

values

python数据类型之内置方法

标签：pytho table get 插入判断 ima result dba 很多

原文地址：https://www.cnblogs.com/zuanzuan/p/9651821.html

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python数据类型之内置方法

一整型

1 int

2 str

3 list

4 dict

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python数据类型之内置方法

一 整型

1 int

2 str

3 list

4 dict

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一整型