help('str')

>>> hash('hello world')
-2288959098694490958
>>> hash(123)
123

>>> class A:
...     x = 10
...     y = 20
...
>>> a = A()
>>> hasattr(a, 'x')
True
>>> hasattr(a, 'z')
False

>>> globals()
{'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <class '_frozen_importlib.BuiltinImporter'>, '__spec__': None, '__annotations__': {}, '__builtins__': <module 'builtins' (built-in)>}
>>>

>>> a = frozenset(range(10))

>>> "{} {}".format("hello", "world")
'hello world'
>>> "{0} {1} {0}".format("hello", "world")
'hello world hello'

>>> "{name} haha {age}".format(name='yhh', age=20)
'yhh haha 20'

>>> "{name} haha {age}".format(**{"name": "yhh", "age": 18})
'yhh haha 20'

>>> "{:.2f}".format(3.1415926)
'3.14'

>>> float(1)
1.0
>>> float('12')
12.0

filter(function, iterable)

>>> def f(s):
...     return s % 2 == 0
...
>>> a = filter(f, [1,2,3,4])
>>> list(a)

>>> exec('print("Hello World")')
Hello World
>>> exec('for i in range(0,3): print(i)')
0
1
2

>>> x = 10
>>> expr = """
... z = 30
... sum = x + y + z
... print(sum)
... """
>>>
>>> def func():
...     y = 20
...     exec(expr)
...     exec(expr, {'x': 1, 'y': 2})
...     exec(expr, {'x': 1, 'y': 2}, {'y': 3, 'z': 4})
...
>>> func()
60
33
34

class A:
...    x = 10
...    y = 10
...    z = 20


>>> delattr(A, 'z')
>>> a = A()
>>> a.x
10
>>> a.z
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'A' object has no attribute 'z'

>>> a = 10
>>> eval('a + 10')
20
>>> eval('pow(a,2)')
100
>>> b = [1,2]
>>> eval('b[1]')
2

>>> complex(1, 2)
(1+2j)
>>> complex("1+2j")
(1+2j)

>>> seq = ['one', 'two', 'three']
>>> for i, element in enumerate(seq):
...     print(i, element)
...
0 one
1 two
2 three

>>> divmod(10, 3)
(3, 1)

dir([object])

>>> class A:
...     x = 10
...     def m():
...         print('haha')
...
>>> a = A()
>>> dir(a)
['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'm', 'x']

>>> dict()
{}
>>> dict(a='a', b='b', c='c')
{'a': 'a', 'b': 'b', 'c': 'c'}
>>> dict([(1,10), (2, 20), (3,30)])
{1: 10, 2: 20, 3: 30}

compile(source, filename, mode[, flags[, dont_inherit]])

>>> str = "for i in range(0,10): print(i)"
>>> c = compile(str, '', 'exec')
>>> exec(c)

>>> class A:
...     a = 10
...     def m1(self):
...         print("m1")
...
...     @classmethod
...     def m2(cls):
...         print(cls.a)
...         # 创建对象，然后再访问方法
...         cls().m1()
...
>>> A.m2()
10
m1

>>> chr(10)
'\n'
>>> chr(78)
'N'
>>> chr(22020)
'嘄'

>>> callable(10)
False

>>> def a():
...     return 1
...
>>> callable(a)
True

>>> class A:
...     def m():
...         pass
...
>>> callable(A)
True

>>> a = A()
>>> callable(a)
>>> callable(a.m)
True

>>> bytes([1,2,3])
b'\x01\x02\x03'
>>> bytes('hello', 'utf-8')
b'hello'
>>> bytes(1)
b'\x00'

>>> a = bytes([1,2,3])
>>> a[1] = 20
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'bytes' object does not support item assignment

class bytearray([source[, encoding[, errors]]])

>>> bytearray('hello', 'utf-8')
bytearray(b'hello')
>>> bytearray(2)
bytearray(b'\x00\x00')
>>> bytearray([1,2,3])
bytearray(b'\x01\x02\x03')
>>> a = bytearray([1,2,3])
>>> a[1] = 20
>>> a
bytearray(b'\x01\x14\x03')

>>> bool('True')
True
>>> bool('true')
True
>>> bool(2)
True

>>> bin(10)
'0b1010'
>>> bin(16)
'0b10000'

>>> ascii('你好hello')
"'\\u4f60\\u597dhello'"

>>> any([0, '', False])
False
>>> any([1, '', False])
True

def all(iterable):
    for element in iterable:
        if not element:
            return False
    return True

all(['a', 'b', 'c', 'd'])

abs(-10)

>>> abs(complex(-10, 1))
10.04987562112089

import json

a = {'a': [1,2,3], 'b': {'t': 'tt', 'b': 123}}
# 转换为json字符串
b = json.dumps(a)

# json字符串转换为map
c = json.loads(b)

os.chown(path, uid, gid);

os.chmod(path, mod)

os.access(path, mode);

os.chdir(path)

>>> import os
>>> retval = os.getcwd()
>>> print ("当前工作目录为 %s" % retval)
当前工作目录为 /Users/user
>>> os.chdir( '/tmp' )
>>> os.getcwd()
'/private/tmp'
>>> os.getcwd()
'/private/tmp'

import os

os.getcwd()

import shutil
shutil.make_archive("out", "zip", "/tmp/test")

import shutil

def move_dir(source, target):
    """
    目录迁移
    :param source:
    :param target:
    :return:
    """
    shutil.move(source, target)

import os

def create_dir(path):
    """
    目录不存在时，主动创建
    :param path:
    :return:
    """
    if not os.path.exists(path):
        os.makedirs(path)

import os

def list_dir(path):
    """
    获取目录下所有文件
    :param path:
    :return:
    """
    for file in os.listdir(path):
        print(file)

with open('demo.txt', 'w+') as f:
    f.write("hello")
    f.write("world")
    f.flush()

with open('demo.txt', 'w+') as f:
    f.writelines(["12", "34"])
    f.flush()

for line in iopen('demo.txt', 'r+'):
	print(f)

with open('demo.txt', 'r+') as f:
    for line in f.readlines():
        print(line)

import os

size = os.path.getsize('/tmp/img/tmp.jpg')
print(size)

open(file, mode='r', buffering=-1, encoding=None, errors=None, newline=None, closefd=True, opener=None)

>>> str = input("请输入：")
请输入：yhh
>>> print(str)
yhh

>>> class A:
...     a  = 1
...     b = 2
...
>>> a = A()
>>> getattr(a, 'a')
1
>>> a.a
1
# 获取一个不存在的属性值
>>> getattr(a, 'c')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'A' object has no attribute 'c'
# 如果不存在，则返回默认值
>>> getattr(a, 'c', 3)
3