深入理解Python3 内置函数大全

#coding=utf-8
# builtin_function.py 内置函数
import os

def fun():
  all([True, False]) # 迭代器(为空or)所有元素为true,返回true => False
  any([True, False]) # 迭代器任意一个元素为true,返回true => True

  num = abs(-1.23) # 绝对值
  num = pow(5, 3) # 幂次方 x**y =>125
  num = pow(5, 3, 3) # 幂次方再取余 (x**y) % z => 2
  num = round(1.23) # 返回浮点数近似值,默认保留0位,且四舍五入
  num = round(1.23, 5) # 5为保留小数点后位数
  num = sum([1, 2, 3, 4, 5]) # 对列表数字求和
  strs = ascii(os) # 返回对象的ascii字符串形式
  strs = bin(123) # 整数转为二进制字符串(若被转对象非int类型可在__index__里定义)
  boolean = bool(0) # 获取真假(假:None / False / 任何类型的0 / 空""()[]{} / __bool__返回False / __len__返回0)
  bytes = bytearray("You were, are and will be in my heart!", "utf-8") # 字符串(字符串,编码):按编码转为字节序列 / 数字(数字):生成相应大小的空数组 / 无参():0数组
  bytes = bytes("You were, are and will be in my heart!", "utf-8") # 同bytearray(),但是不可变
  strs = chr(123) # 整数(Unicode)转为char类型(范围[0, 1 114 111])
  num = ord("{") # char类型转为整数(Unicode)
  num = complex("1+2j") # 将字符串或数字转为复数(不能含有空格)
  num = float('1.1') # 构建浮点数
  strs = format(123,'f') # 格式化(类型:x,b,f... / 位移:>(>10),<,^ / 长度:5 / E)
  strs = hex(123) # 将整数转为16进制字符串
  strs = oct(123) # 十进制转成8进制字符串
  num = int(123.1) # 转为整数
  strs = str(123) # 将对象转为字符串
  strs = str(b"123", "utf-8")
  elem = max([1,2,3,4], [2,4,6]) # 可接收1个iterable,或多个元素 => [2, 4, 6]
  elem = max(1,2,3,4) # => 4
  elem = max([1,2,3,4, 6], key = lambda x : x == 2) # => 2
  elem = min(1,2,3,4) # 与max相反

  exe = compile("print('O_O')", filename = 'strs', mode='exec') # 编译为代码, mode(编译模式:可执行语句'exec',单个语句'eval',交互式语句'single')
  exec(exe) # 执行已编译代码
  exec("print('O_O')") # 执行String未编译代码
  eval(compile("print('O_O')", filename = 'strs', mode='eval')) # 不接受字符串类型

  delattr(Clazz("Hello!"), "name") # 删除某对象属性 = del clazz.name 详情见 类 文章的 反射 代码块(https://www.jb51.net/article/128897.htm)
  setattr(Clazz("Hello!"), "name", "World!") # 给对象某属性赋值
  strs = getattr(Clazz("Hello!"), "name") # 获取某个对象的属性值
  strs = getattr(Clazz("Hello!"), "name", -1) # -1为未找到属性的返回
  boolean = hasattr(Clazz("Hello!"), "name") # 该对象是否有该属性
  lists = dir(Clazz("Hello!")) # 查看函数
  clazz = type(os) # 获取类型
  dicts = globals() # 获取当前全局函数与对象
  dicts = locals() # 获取当前局部函数与对象
  dicts = vars() # 同locals() (__dict__)
  dicts = vars(Clazz("Hello!"))
  num = hash(Clazz("Hello!")) # 获取某对象的hash值 
  help(os) # 获取某对象的帮助文档
  num = id(os) # 获取某对象的id
  boolean = isinstance(Clazz("Hello!"), Clazz) # 对象是否是该类的实例
  boolean = issubclass(Clazz, Clazz) # 该类(前)是否是该类(后)的子类(包括自己)
  strs = repr(os) # 将对象转为字符串表达形式
  # - super() # 代理父类对象,详情见 类 文章(https://www.jb51.net/article/88315.htm)
  # - memoryview(obj) # 内存视图,详解 数据结构 文章(https://www.jb51.net/article/128892.htm)

  dics = dict() # 创建字典
  tups = divmod(10, 5) # 返回元组,(商(10/5),余数(10%5))
  lists = enumerate(['a', 'b', 'c']) # 返回枚举对象
  lists = filter(lambda x: True if (ord(x) > 66) else False, ['a', 'b', 'c']) # function为Frue保留,False移除
  sets = frozenset([1, 2, 3]) # 返回新的frozenset对象(集合)
  num = len([1, 2, 3]) # 长度
  lists = list((1, 'a')) # 转为list类型
  tups = tuple([1, 2, 3]) # 转为tuple元组类型
  ran = range(5) # 不可变序列
  ran = range(0,5)
  ran = range(0,5,2) # (起始,结束,增加量)
  sets = set([1,2,3]) # 返回set集合
  maps = map(lambda x, y: x*y, [1, 2, 3], [65, 66, 67, 68]) # 返回一个迭代器,元素通过自定义函数筛选,可接收多个iterable参数 => [65, 132, 201]
  iters = zip(["A", "B", "C", "D", "E", "F"], [1, 2, 3]) # 创建新的迭代器, 聚合每个迭代器元素 => [('A', 1), ('B', 2), ('C', 3)]
  iters = iter([1, 2, 3, 4, 5]) # 返回一个迭代器对象
  elem = next(iters) # 从迭代器中获取下个元素; 实现原理见 内置函数 文章 lis 块代码(https://www.jb51.net/article/128890.htm)
  iters = reversed([1,2,3]) # 返回反向的遍历器 => [3, 2, 1]
  lists = [1,2,3,4,5][slice(3)] # 切片 => [1, 2, 3]
  lists = [1,2,3,4,5][slice(1,3)] # [slice(3) == slice(None, 3, None) / slice(1,3) == slice(1, 3, None) / slice(1,3,1) == slice(1, 3, 1)
  lists = sorted([2,5,3,1,4]) # 排序 => [1, 2, 3, 4, 5]
  lists = sorted(['a','B',';','t','D','1'], key = lambda x : ord(x), reverse = True) # key:比较键的函数, reverse是否反向遍历


  strs = input("请输入数据:") # 输入数据
  f = open("temp.txt", "r+") # 打开文件,详情见os文章
  print("字符串%d"%123) # 打印字符 => 字符串123
  print("字","符", "串", sep="-") # sep为分隔 => 字-符-串
  print("字","符", "串", sep="-", end="\r\n") # end为尾部 => 字-符-串/r/n
  print("字","符", "串", sep="-", end="\r\n", file=open("temp.txt","w+")) # 打印到文件


class Clazz:
  def __init__(self, name):
    self.name = name;

  @classmethod # 将函数包装成类方法
  def setName_cls(cls, name):
    pass

  @staticmethod # 将函数包装成静态方法
  def setName_sta(name):
    pass

  def getname(self):
    return self.name
  def setname(self, value):
    self.name = value
  def delname(self):
    del self.name

  # property(fget=None, fset=None, fdel=None, doc=None) # 返回一个property 属性
  # property 为属性方法, 有两种实现方式,详情见 类 文章的 属性方法代码块(https://www.jb51.net/article/68235.htm) 
  x = property(getname, setname, delname)

 

if __name__ == "__main__":
  fun()

  # property 的使用
  c = Clazz("柳岩")
  print(c.x) # => 柳岩
  c.x = '汤唯'
  print(c.getname()) # => 汤唯
  del c.x