By admin
Hello，大家好，我是Alex~
今天我继续上次分享的52个基础代码剩下的22个来进行分享
一起来看看都有哪些吧！
31 一键帮助
返回对象的帮助文档
In [1]: help(xiaoming)
Help on Student in module __main__ object:
class Student(builtins.object)
Methods defined here:
__init__(self, id, name)
__repr__(self)
Data descriptors defined here:
__dict__
dictionary for instance variables (if defined)
__weakref__
list of weak references to the object (if defined)
32 对象门牌号 返回对象的内存地址
In [1]: id(xiaoming)
Out[1]: 98234208
33 获取用户输入 获取用户输入内容
In [1]: input()
aa
Out[1]: 'aa'
34 转为整型 int(x, base =10) , x可能为字符串或数值，将x 转换为一个普通整数。如果参数是字符串，那么它可能包含符号和小数点。如果超出了普通整数的表示范围，一个长整数被返回。
In [1]: int('12',16)
Out[1]: 18
35 isinstance判断object是否为类classinfo的实例，是返回true
In [1]: class Student():
...: def __init__(self,id,name):
...: self.id = id
...: self.name = name
...: def __repr__(self):
...: return 'id = '+self.id +', name = '+self.name
In [2]: xiaoming = Student(id='001',name='xiaoming')
In [3]: isinstance(xiaoming,Student)
Out[3]: True
36 父子关系鉴定
In [1]: class undergraduate(Student):
...: def studyClass(self):
...: pass
...: def attendActivity(self):
...: pass
In [2]: issubclass(undergraduate,Student)
Out[2]: True
In [3]: issubclass(object,Student)
Out[3]: False
In [4]: issubclass(Student,object)
Out[4]: True
如果class是classinfo元组中某个元素的子类，也会返回True
In [1]: issubclass(int,(int,float))
Out[1]: True
37 创建迭代器类型使用iter(obj, sentinel), 返回一个可迭代对象, sentinel可省略(一旦迭代到此元素，立即终止)
In [1]: lst = [1,3,5]
In [2]: for i in iter(lst):
...: print(i)
...:
1
3
5
In [1]: class TestIter(object):
...: def __init__(self):
...: self.l=[1,3,2,3,4,5]
...: self.i=iter(self.l)
...: def __call__(self): #定义了__call__方法的类的实例是可调用的
...: item = next(self.i)
...: print ("__call__ is called,fowhich would return",item)
...: return item
...: def __iter__(self): #支持迭代协议(即定义有__iter__()函数)
...: print ("__iter__ is called!!")
...: return iter(self.l)
In [2]: t = TestIter()
In [3]: t() # 因为实现了__call__，所以t实例能被调用
__call__ is called,which would return 1
Out[3]: 1
In [4]: for e in TestIter(): # 因为实现了__iter__方法，所以t能被迭代
...: print(e)
...:
__iter__ is called!!
1
3
2
3
4
5
38 所有对象之根object 是所有类的基类
In [1]: o = object()
In [2]: type(o)
Out[2]: object
39 打开文件返回文件对象
In [1]: fo = open('D:/a.txt',mode='r', encoding='utf-8')
In [2]: fo.read()
Out[2]: '\ufefflife is not so long,\nI use Python to play.'
mode取值表：
40 次幂base为底的exp次幂，如果mod给出，取余
In [1]: pow(3, 2, 4)
Out[1]: 1
41 打印
In [5]: lst = [1,3,5]
In [6]: print(lst)
[1, 3, 5]
In [7]: print(f'lst: {lst}')
lst: [1, 3, 5]
In [8]: print('lst:{}'.format(lst))
lst:[1, 3, 5]
In [9]: print('lst:',lst)
lst: [1, 3, 5]
42 创建属性的两种方式返回 property 属性，典型的用法：
class C:
def __init__(self):
self._x = None
def getx(self):
return self._x
def setx(self, value):
self._x = value
def delx(self):
del self._x
# 使用property类创建 property 属性
x = property(getx, setx, delx, "I'm the 'x' property.")
使用python装饰器，实现与上完全一样的效果代码：
class C:
def __init__(self):
self._x = None
@property
def x(self):
return self._x
@x.setter
def x(self, value):
self._x = value
@x.deleter
def x(self):
del self._x
43 创建range序列
range(stop)
range(start, stop[,step])
生成一个不可变序列：
In [1]: range(11)
Out[1]: range(0, 11)
In [2]: range(0,11,1)
Out[2]: range(0, 11)
44 反向迭代器
In [1]: rev = reversed([1,4,2,3,1])
In [2]: for i in rev:
...: print(i)
...:
1
3
2
4
1
45 四舍五入四舍五入，ndigits代表小数点后保留几位：
In [11]: round(10.0222222, 3)
Out[11]: 10.022
In [12]: round(10.05,1)
Out[12]: 10.1
46 转为集合类型返回一个set对象，集合内不允许有重复元素：
In [159]: a = [1,4,2,3,1]
In [160]: set(a)
Out[160]: {1, 2, 3, 4}
47 转为切片对象class slice(start, stop[, step])
返回一个表示由 range(start, stop, step) 所指定索引集的 slice对象，它让代码可读性、可维护性变好。
In [1]: a = [1,4,2,3,1]
In [2]: my_slice_meaning = slice(0,5,2)
In [3]: a[my_slice_meaning]
Out[3]: [1, 2, 1]
48 拿来就用的排序函数排序：
In [1]: a = [1,4,2,3,1]
In [2]: sorted(a,reverse=True)
Out[2]: [4, 3, 2, 1, 1]
In [3]: a = [{'name':'xiaoming','age':18,'gender':'male'},{'name':'
...: xiaohong','age':20,'gender':'female'}]
In [4]: sorted(a,key=lambda x: x['age'],reverse=False)
Out[4]:
[{'name': 'xiaoming', 'age': 18, 'gender': 'male'},
{'name': 'xiaohong', 'age': 20, 'gender': 'female'}]
49 求和函数求和：
In [181]: a = [1,4,2,3,1]
In [182]: sum(a)
Out[182]: 11
In [185]: sum(a,10) #求和的初始值为10
Out[185]: 21
50 转元组tuple() 将对象转为一个不可变的序列类型
In [16]: i_am_list = [1,3,5]
In [17]: i_am_tuple = tuple(i_am_list)
In [18]: i_am_tuple
Out[18]: (1, 3, 5)
51 查看对象类型class type(name, bases, dict)
传入一个参数时，返回 object 的类型：
In [1]: class Student():
...: def __init__(self,id,name):
...: self.id = id
...: self.name = name
...: def __repr__(self):
...: return 'id = '+self.id +', name = '+self.name
...:
...:
In [2]: xiaoming = Student(id='001',name='xiaoming')
In [3]: type(xiaoming)
Out[3]: __main__.Student
In [4]: type(tuple())
Out[4]: tuple
52 聚合迭代器创建一个聚合了来自每个可迭代对象中的元素的迭代器：
In [1]: x = [3,2,1]
In [2]: y = [4,5,6]
In [3]: list(zip(y,x))
Out[3]: [(4, 3), (5, 2), (6, 1)]
In [4]: a = range(5)
In [5]: b = list('abcde')
In [6]: b
Out[6]: ['a', 'b', 'c', 'd', 'e']
In [7]: [str(y) + str(x) for x,y in zip(a,b)]
Out[7]: ['a0', 'b1', 'c2', 'd3', 'e4']
好了，今天我的52个python基础代码分享到这里就结束了
希望能够给大家带来一个帮助
喜欢就点个赞哦~