Built-in Functions（68个）
1、数学方法
abs() sum() pow() min() max() divmod() round()
2、进制转换
bin() oct() hex()
3、简单数据类型
- 整数：int()
- 浮点数：float()
- 字符\字符串：str() repr() ascii() ord() chr() format()
- 字节：bytes() bytearray()
- 布尔：bool()
- 复数：complex()
4、数据结构
- 列表：list() slice() range()
- 元组：tuple()
- 字典：dict() hash()
- 集合：set() frozenset()
- 方法：len() zip() all() any() iter() filter() next() sorted() reversed() enumerate() map() memoryview()
5、面向对象
setattr() getattr() delattr() hasattr()
super() property()
staticmethod() classmethod()
isinstance() issubclass()
6、系统方法
dir() help() id() object() type()
input() open() print()
eval() exec() compile()
vars() locals() globals()
callable() __import__()
参考：https://docs.python.org/3.5/library/functions.html
print(abs(-1)) # 绝对值 1 print(divmod(5, 2)) # 取商和余数 (2, 1) # 四舍五入 print(round(1.4)) # 1 print(round(1.5)) # 2 print(round(1.6)) # 2 # 次方，相当于x**y print(pow(2, 8)) # 256 print(bin(2)) # 转为二进制 0b10 print(oct(12)) # 转8进制 0o14 print(hex(20)) # 转16进制 0x14 print(bool(1)) # 转为布尔值 True # 转为int s = "12" i = int(s) print(type(s), type(i)) # <class 'str'> <class 'int'> # 转字符串 i = 12345 s =str(i) print(type(i), type(s)) # <class 'int'> <class 'str'> print([ascii([1,2,3])]) # 转为字符串 ['[1, 2, 3]'] # 转为可打印对象representation 表现 s = 123456 r =repr(s) print(type(s), type(r)) # <class 'int'> <class 'str'> # ascii码 print(chr(100)) # d print(ord("a")) # 97 print(bytes("我是中国人", encoding="utf-8")) # b'\xe6\x88\x91\xe6\x98\xaf\xe4\xb8\xad\xe5\x9b\xbd\xe4\xba\xba' b = bytearray("abc", encoding="utf-8") # 转为字节数组 print(b) # bytearray(b'abc') print(b[0]) # 97 b[0] = 100 print(b) # bytearray(b'dbc') # 新建字典对象 d1 = {} d2 = dict() d3 = dict(name = "Tom", age = 23) print(d1) # {} print(d2) # {} print(d3) # {'age': 23, 'name': 'Tom'} # 获取散列值 res = hash(1) print(res) # 1 res = hash("Tom") # -1433634475463391166 print(res) # 不可变集合 st = frozenset([1,2,3,4]) print(type(st)) # <class 'frozenset'> # 生成列表 lst1 = [] lst2 = list() lst3 = list((1,2,3)) print(lst1) # [] print(lst2) # [] print(lst3) # [1, 2, 3] # 计算长度 print(len([1,2,3])) # 3 # 最大最小值 lst = [1,3,4,5,8,6,9] print(max(lst)) # 9 print(min(lst)) # 1 # 求和 lst = [i for i in range(5)] print(sum(lst)) # 10 # 切片 lst = [x for x in range(10)] s = slice(2,5) print(lst[s]) # [2, 3, 4] # 枚举 for index, value in enumerate(range(1,5)): print(index, value) """ 0 1 1 2 2 3 3 4 """ print(all([1,2,3])) # 所有都是真的 True print(all([1,2,0])) # False print(any([1,2,1])) # 至少存在一个真的 True print(any([0])) # False # 元组 t1 = () t2 = (1,) t3 = tuple() print(type(t1)) # <class 'tuple'> print(type(t2)) # <class 'tuple'> print(type(t3)) # <class 'tuple'> # 反转 lst = [1, 2, 3] print(reversed(lst)) # <list_reverseiterator object at 0x0000000003A54A90> # lambda 与 三元运算符 lamb = lambda x : 3 if x < 5 else x print(lamb(5)) # 5 # 过滤 res = filter(lambda x: x>5, range(10)) for i in res: print(i,end=" ") # 6 7 8 9 print() # 映射 res = map(lambda x: x*x, range(10)) for i in res: print(i, end=" ") # 0 1 4 9 16 25 36 49 64 81 print() """ 等价于： res = [lambda x: x*x for x in range(10)] res = [x*x for x in range(10)] """ # 浓缩 import functools # py3 res = functools.reduce(lambda x, y: x + y, range(10)) print(res) # 45 # 排序 dct ={"0": 99, "1": 98, "6": 11, "5": 45} print(dct) # {'6': 11, '0': 99, '1': 98, '5': 45} print(sorted(dct)) # ['0', '1', '5', '6'] print(sorted(dct.items())) # [('0', 99), ('1', 98), ('5', 45), ('6', 11)] print(sorted(dct.items(), key=lambda x: x[1])) # [('6', 11), ('5', 45), ('1', 98), ('0', 99)] # 拉链，这个叫法很形象 a = [1, 2, 3, 4, 5] b = ["a", "b", "c", "d", "e"] z = zip(a, b) print(z) # <zip object at 0x0000000003FBE1C8> print([i for i in z]) # [(1, 'a'), (2, 'b'), (3, 'c'), (4, 'd'), (5, 'e')] # 转为迭代器 lst = [1, 2, 3] ilst = iter(lst) print(type(lst),type(ilst)) # <class 'list'> <class 'list_iterator'> # 相当于生成器的__next()__ 方法 lst = range(5) print(type(ilst)) # <class 'range'> ilst = iter(lst) print(type(ilst)) # <class 'range_iterator'> print(next(ilst)) # 0 print(next(ilst)) # 1 # 判断是否为某个类的实例 d ={} print(isinstance(d, dict)) # True # 导入包 动态加载类和函数 __import__("iterator_test") print() print(dir(d1)) # 查看方法 """ ['__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'] """ print(help(divmod)) # 查看帮助 """ Help on built-in function divmod in module builtins: divmod(...) divmod(x, y) -> (div, mod) Return the tuple ((x-x%y)/y, x%y). Invariant: div*y + mod == x. """ # 对象id a = 1 print(id(a)) # 1430299072 # 打印局部变量 def foo(): a = 1 print(vars()) # {'a': 1} foo() # 打印局部变量 def foo(): a = 1 print(locals()) # {'a': 1} foo() print(globals()) # 打印当前文件的所有全局变量，key-value形式返回 """ {'code': '\nfor i in range(5):\n print(i, end=" ")\n', '__cached__': None, 'value': 4, 'index': 3, 'd1': {}, 'b': bytearray(b'dbc'), 'lamb': <function <lambda> at 0x00000000024E8730>, '__package__': None, 'st': frozenset({1, 2, 3, 4}), ... """ code = """ for i in range(5): print(i, end=" ") """ exec(code) # 运行代码 0 1 2 3 4 x = 1 print("eval:", eval("x+1")) # eval: 2 def sayHello():pass print(callable(sayHello)) # True
