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python3

>>>for i in range(4):
...

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import sys


num = len(sys.argv)

if num != 3:
    print('Usage: xxx.py argv1 argv2')
else:
    print('argu[0] is ' + sys.argv[0])
    print('argu[1] is ' + sys.argv[1])
    print('argu[2] is ' + sys.argv[2])


chmod u+x xxx.py

./argvPass.py 1 22
argu[0] is ./argvPass.py
argu[1] is 1
argu[2] is 22

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#!/usr/bin/python3
# -*- coding: utf-8 -*-

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+
 -
*
/
//(取商)
%(取余)
**

int
float
decimal
fraction(分数)
comlex number(复数)

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'(single quote)
"(double quote)
\(转义)
r(元字符)
'''
"""

+
*

index
string[-1]
string[0:2]

len()

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list = [xx, x, ...]

index
list[index]
list[start:stop]

method
append()
pop()
del()
...

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a, b = 0, 1
while b < 10:
    print(b, end=',')
	a, b = b, a+b

 #多重赋值(multiple assignment)
 #关键字参数(keyword argument)

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a = input(int('Please input an int: '))

whiel a < 50:
	a += 1

print(a)

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x = int(input("please input an int: "))

if x < 0:
    x = 0
    print('Negative changed to zero')
elif x == 0:
    print('Zero')
elif x == 1:
    print('Single')
else:
    print('More')

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words = ['a', 'bb', 'ccc']

for w in words:
	print(w, len(w))


'''
如果需要修改迭代中的序列，建议先制作副本，遍历一个序列并不会隐式地创建一个副本
'''
words = ['a', 22, 'ccc']
for w in words[:]:
    if type(w) is int:
		words.insert(0, w)

words
[22, 'a', 22, 'ccc']

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for i in range(5):
	print(i)


for i in range(0, 101, 10):
	print(i)


a = [1, 22, 'A', 'AA']
for i in range(len(a))
	print(i, a[i])

list(range(5))
[0, 1, 2, 3, 4]

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print(range(10))
range(0, 10)

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while True:
    pass

class emptyClass:
    pass

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def fib(n):
	"""function's documentation
	   print a Fibonacci series up to n.
	"""
    a, b = 0, 1
	while a < n:
		print(a, end='  ')
		a, b = b, a+b
	print()

fib(100)

f = fib
f(100)

print(fib())
None

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def ask_ok(prompt, retries=4, reminder='Please try again!'):
    while True:
        ok = input(prompt)
        if ok in ('y', 'ye', 'yes'):
            return True
        if ok in ('n', 'no', 'nop', 'nope'):
            return False
        retries = retries - 1
        if retries < 0:
            raise ValueError('invalid user response')
        print(reminder)

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def parrot(voltage, state='a stiff', action='voom', type='Norwegian Blue'):
    print("-- This parrot wouldn't", action, end=' ')
    print("if you put", voltage, "volts through it.")
    print("-- Lovely plumage, the", type)
    print("-- It's", state, "!")



parrot(1000)                                          # 1 positional argument
parrot(voltage=1000)                                  # 1 keyword argument
parrot(voltage=1000000, action='VOOOOOM')             # 2 keyword arguments
parrot(action='VOOOOOM', voltage=1000000)             # 2 keyword arguments
parrot('a million', 'bereft of life', 'jump')         # 3 positional arguments
parrot('a thousand', state='pushing up the daisies')  # 1 positional, 1 keyword

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def shop(kind, *arguments, **keywords):
    print("-- Do you have any ", kind, "?")
    print("-- I'm sorry, we're all out of ", kind)
    for arg in arguments:
        print(arg)
    print('\n-----\n')
    for kw in keywords:
        print(kw, ':', keywords[kw])


shop('Kind', 'arg1', 'arg2', kw1='KW1', kw2='KW2', kw3='KW3')

"""
-- Do you have any  Kind ?
-- I'm sorry, we're all out of  Kind
arg1
arg2

-----

kw3 : KW3
kw1 : KW1
kw2 : KW2
"""

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def arb(*args):
	for arg in args:
		print(arg)

art(1, 22, 'CCC')

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list(range(5))
[0, 1, 2, 3, 4]

args = [5]
list(range(*args))
[0, 1, 2, 3, 4]

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def lambdaTest(n):
	return lambda x: x + n

f = lambdaTest(10)
f(1)
11

f(5)
15

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def func():
    """Document it.

	This func just print one argument.
	"""

	print(sys.argv[1])


print(func.__doc__)

Document it.
    This func just print one argument.

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def f(name: str, age: int = 18) -> str:
    print("Annotations: ", f.__annotations__)
    print("Arguments: ", name, age)
    return name + 'and' + str(age)

f('Zhang21')

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 #列表解析提供了一个简洁的方式来创建列表
l = []
for i in range(10):
    l.append(i**2)

 #lambda
l = list(map(lambda i: i**2, range(10)))

 #or
l = [x**2 for i in range(10)]


[(x, y) for x in [1, 2, 3] for y in [3, 2, 1] if x != y]

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l = [
    [1, 2, 3, 4],
	[5, 6, 7, 8],
	[9, 10 ,11, 12]
]

[[row[i] for row in l] for i in range(4)]

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a = [1, 2, 3, 4]

del a[0]

del a[1:3]

del a[:]

del a

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t = (123, 321, 'hello')

tt = t, ('a', 'bb')

(123, 321, 'hello), ('a', 'bb')

 #对元组赋值会出错
t[0] = 888
TypeError: 'tuple' object does not support item assignment


 #序列拆包(unpacking)
 #要求变量数量等于元素数量
x, y, z = t

x
123

y
321

z
'hello'

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alpha = {'a', 'b', 'c', 'a'}

alpha
{'c', 'b', 'a'}

'c' in alpha
True


 #数学运算
a = set('abracadabra')
b = set('alacazam')

a | b
a & b
a - b
a ^ b


 #集合解析
{x for x in 'abcdefgabc' if x not in 'abc'}

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info = {'name': 'AA', 'id': 1, 'tel': 155}
info['addr'] = 'Chengdu'

info
info['name']

del info['id']

list(info.keys())
print(info.values())
print(info.items())


 #dict()构造函数
dict([('name', 'A'), ('age', 11)])
dict({'name': 'A', 'age': 11})
dict(name='zhang', age=11)

 #字典解析
{x: x**2 for x in (2, 4, 6)}

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info = {'name': 'AA', 'age': 11}
for k, v in info.items():
    print(k, v, sep=':')

name:AA
age:11

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for i, v in enumerate(['a', 'b', 'c']):
    print(i, v)

0 a
1 b
2 c

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aa = [1, 2, 3]
bb = ['a', 'b', 'c']

for a, b in zip(aa, bb):
    print('{0}, {1}'.format(a, b))

1, a
2, b
3, c

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4

for i in reversed(range(6)):
    print(i, end=',')

5,4,3,2,1,0,

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l = ['ac', 'fb', 'nx', 'by']
for i in sorted(l):
    print(i)

ac
by
fb
nx


ll = ['ac', 'fb', 'nx', 'by', 'ac', 'by']
for i in sorted(set(ll)):
    print(i)

ac
by
fb
nx

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 #Fibonacci numbers module

def fib(n):
    a, b = 0, 1
	while b < n:
	    print(b, end=' , ')
		a, b = b, a+b
	print()

def fib2(n):
	result = []
	a, b = 0, 1
	while b < n:
		result.appen(b)
		a, b = b, a+b
	return result

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cd /path

python3

>>> import fibo
>>> fibo.fb(100)
1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89,
>>> fibo.fib2(100)
[1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89]
>>> fibo.__name__
'fibo'
>>> fibo.__str__()
module 'fibo' from '/path/fibo.py'

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 #fibo模块名并没有被定义
from fibo import fib, fib2

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 #这会导入除了以下划线开头的所有名称
from fibo import *

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import fibo as fib

fib.fib(100)
fib.fib2(100)


from fibo import fib2 as fibonacci

fibonacci(100)

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if __name__ == "__main__":
    import sys
	fib(int(sys.argv[1]))


python3 fibo.py {args}

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import sys

sys.ps1
'>>>'
sys.ps2
'...'

sys.ps1 = '<<<'
sys.ps1
'<<<'


 #查看PYTHONPATH
sys.path.__str__
 #添加PYTHONPATH
sys.path.append('/home/zhang/venv/python')

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import fibo, sys

dir(fibo)
['__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', '__spec__', 'fib', 'fib2']


dir(sys)
['__displayhook__', '__doc__', '__excepthook__', '__interactivehook__', '__loader__', '__name__', '__package__', '__spec__', '__stderr__', '__stdin__', '__stdout__', '_clear_type_cache', '_current_frames', '_debugmallocstats', '_getframe', '_home', '_mercurial', '_xoptions', 'abiflags', 'api_version', 'argv', 'base_exec_prefix', 'base_prefix', 'builtin_module_names', 'byteorder', 'call_tracing', 'callstats', 'copyright', 'displayhook', 'dont_write_bytecode', 'exc_info', 'excepthook', 'exec_prefix', 'executable', 'exit', 'flags', 'float_info', 'float_repr_style', 'getallocatedblocks', 'getcheckinterval', 'getdefaultencoding', 'getdlopenflags', 'getfilesystemencoding', 'getprofile', 'getrecursionlimit', 'getrefcount', 'getsizeof', 'getswitchinterval', 'gettrace', 'hash_info', 'hexversion', 'implementation', 'int_info', 'intern', 'last_traceback', 'last_type', 'last_value', 'maxsize', 'maxunicode', 'meta_path', 'modules', 'path', 'path_hooks', 'path_importer_cache', 'platform', 'prefix', 'ps1', 'ps2', 'setcheckinterval', 'setdlopenflags', 'setprofile', 'setrecursionlimit', 'setswitchinterval', 'settrace', 'stderr', 'stdin', 'stdout', 'thread_info', 'version', 'version_info', 'warnoptions']


 #它不会列出内建函数和变量的名称，除非如下操作
import builtins
dir(builtins)

['ArithmeticError', 'AssertionError', 'AttributeError', 'BaseException', 'BlockingIOError', 'BrokenPipeError', 'BufferError', 'BytesWarning', 'ChildProcessError', 'ConnectionAbortedError', 'ConnectionError', 'ConnectionRefusedError', 'ConnectionResetError', 'DeprecationWarning', 'EOFError', 'Ellipsis', 'EnvironmentError', 'Exception', 'False', 'FileExistsError', 'FileNotFoundError', 'FloatingPointError', 'FutureWarning', 'GeneratorExit', 'IOError', 'ImportError', 'ImportWarning', 'IndentationError', 'IndexError', 'InterruptedError', 'IsADirectoryError', 'KeyError', 'KeyboardInterrupt', 'LookupError', 'MemoryError', 'NameError', 'None', 'NotADirectoryError', 'NotImplemented', 'NotImplementedError', 'OSError', 'OverflowError', 'PendingDeprecationWarning', 'PermissionError', 'ProcessLookupError', 'ReferenceError', 'ResourceWarning', 'RuntimeError', 'RuntimeWarning', 'StopIteration', 'SyntaxError', 'SyntaxWarning', 'SystemError', 'SystemExit', 'TabError', 'TimeoutError', 'True', 'TypeError', 'UnboundLocalError', 'UnicodeDecodeError', 'UnicodeEncodeError', 'UnicodeError', 'UnicodeTranslateError', 'UnicodeWarning', 'UserWarning', 'ValueError', 'Warning', 'ZeroDivisionError', '_', '__build_class__', '__debug__', '__doc__', '__import__', '__loader__', '__name__', '__package__', '__spec__', 'abs', 'all', 'any', 'ascii', 'bin', 'bool', 'bytearray', 'bytes', 'callable', 'chr', 'classmethod', 'compile', 'complex', 'copyright', 'credits', 'delattr', 'dict', 'dir', 'divmod', 'enumerate', 'eval', 'exec', 'exit', 'filter', 'float', 'format', 'frozenset', 'getattr', 'globals', 'hasattr', 'hash', 'help', 'hex', 'id', 'input', 'int', 'isinstance', 'issubclass', 'iter', 'len', 'license', 'list', 'locals', 'map', 'max', 'memoryview', 'min', 'next', 'object', 'oct', 'open', 'ord', 'pow', 'print', 'property', 'quit', 'range', 'repr', 'reversed', 'round', 'set', 'setattr', 'slice', 'sorted', 'staticmethod', 'str', 'sum', 'super', 'tuple', 'type', 'vars', 'zip']

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sound/                          Top-level package
      __init__.py               Initialize the sound package
      formats/                  Subpackage for file format conversions
              __init__.py
              wavread.py
              wavwrite.py
              aiffread.py
              aiffwrite.py
              auread.py
              auwrite.py
              ...
      effects/                  Subpackage for sound effects
              __init__.py
              echo.py
              surround.py
              reverse.py
              ...
      filters/                  Subpackage for filters
              __init__.py
              equalizer.py
              vocoder.py
              karaoke.py
              ...

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import sound.effects.echo

from sound.effects import echo

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 #这意味着from sound.effects import *只会导入以下子模块
__all__ = ["echo", "surround", "reverse"]

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 #Absolute
from sound.effects import echo


 #Relative
from . import echo
from .. import formats
from ..filter import equalizer

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for x in range(1, 6):
    print(repr(x).rjust(2), repr(x**2).rjust(3), end=' ')
	print(repr(x**3).rjust(4))

 #Or
for x in range(1, 6):
    print('{0:2d} {1:3d} {2:4d}'.format(x, x**2, x**3))


  1   1    1
  2   4    8
  3   9   27
  4  16   64
  5  25  125

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>>> '12'.zfill(5)
'00012'
>>>
>>> '-3.14'.zfill(7)
'-003.14'
>>>
>>> '3.1415678'.zfill(5)
'3.1415678'

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 #{}
print('We are {} who say {} is "{}!".format('A', 'BB', 'WONDERFUL'))
We are A who say BB is "WONDERFUL!"


 #括号中的数字用来指向传入的位置
 #{index},从0开始
print('{0} and {1}'.format('A', 'BB'))
A and BB

print('{1} and {0}'.format('A', 'BB'))
BB and A


 #关键字参数
print('My name is {name}, I\'m {age} years old!'.format(name='Zhang21', age=21))
My name is Zhang21, I'm 21 years old!


 #位置参数和关键字参数的组合
print('The story of {0}, {1}, and {other}'.format('A', 'BB', other='CCC'))
The story of A, BB, and CCC


'''
!a, 应用ascii()
!s, 应用str()
!r, 应用repr()
:, 更好的控制格式
:5
:7d
:.3f
'''
print('My full name is {!s}'.format('Zhang21'))
My full name is Zhang21

print('My full name is {!r}'.format('Zhang21'))
My full name is 'Zhang21'

print('The value of {} is approximately {:.3f}'.format('PI', 3.141567))
The value of PI is approximately 3.142

info = {'A': 68, 'BB': 79, 'CCC': 89}
for k, v in info.items():
     print('{0:5} ==> {1:6d}'.format(k, v))

A     ==>     68
BB    ==>     79
CCC   ==>     89

print('A: {A:d}; B: {BB:d}, C: {CCC:d}'.format(**info))
A: 68; B: 79, C: 89

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print('The value of %s is approximately %5.3f' % ('PI', 3.1415678))
The value of PI is approximately 3.142

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f = open('/tmp/1.txt, 'r')
f.readline()
'1\n'

f.closed
Fasle

f.close()
f.closed
True

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with open('/tmp/1.txt') as f:
    read_Data = f.read()

f.closed
True


f.read()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: I/O operation on closed file.

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f = open('/tmp/1.txt', 'r+')
f.write('Line4\n')
6

string = ('AAA', 11)
s = str(string)
f.write(s)
11


f = open('/tmp/1.txt', 'rb+')
f.write(b'0123456789abcde')

f.seek(1)
1
f.read(1)
b'1'

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import json
json.dumps([1, 'simple', 'list'])
'[1, "simple", "list"]'

json.dump(x, f)
x = json.load(f)

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 >>> 10 * (1/0)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ZeroDivisionError: division by zero

 >>> 4 + spam*3
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'spam' is not defined

 >>> '2' + 2
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: Can't convert 'int' object to str implicitly

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while True:
    try:
        x = int(input("Please enter a number: "))
        break
    except ValueError:
        print("Oops!  That was no valid number.  Try again...")


 #多个异常放入一个元组
except (RuntimeError, TypeError, NameError):
    pass

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import sys

try:
    f = open('/tmp/1.txt')
    s = f.readline()
    i = int(s.strip())
except OSError as err:
    print('OS error: {}'.format(err))
except ValueError:
    print("Could not convert data to an integer.")
except:
    print("Unexpected erros", sys.exc_info()[0])
    raise

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try:
    sum = 'a' + 1
except TypeError:
    print('TypeError')
else:
    print('else: ', sum)

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>>> raise NameError('HiThere')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: HiThere



>>> try:
...     raise NameError('HiThere')
... except NameError:
...     print('An exception flew by!')
...     raise
...
An exception flew by!
Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
NameError: HiThere

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class Error(Exception):
    """Base class for exceptions in this module."""
    pass

class InputError(Error):
    """Exception raised for errors in the input.

    Attributes:
        expression -- input expression in which the error occurred
        message -- explanation of the error
    """

    def __init__(self, expression, message):
        self.expression = expression
        self.message = message

class TransitionError(Error):
    """Raised when an operation attempts a state transition that's not
    allowed.

    Attributes:
        previous -- state at beginning of transition
        next -- attempted new state
        message -- explanation of why the specific transition is not allowed
    """

    def __init__(self, previous, next, message):
        self.previous = previous
        self.next = next
        self.message = message

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>>> try:
...     raise KeyboardInterrupt
... finally:
...     print('Goodbye, world!')
...
Goodbye, world!
KeyboardInterrupt
Traceback (most recent call last):
  File "<stdin>", line 2, in <module>

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with open("myfile.txt") as f:
    for line in f:
        print(line, end="")

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def scope_test():
    def do_local():
        spam = "local spam"

    def do_nonlocal():
        nonlocal spam
        spam = "nonlocal spam"

    def do_global():
        global spam
        spam = "global spam"

    spam = "test spam"

    do_local()
    print("After local assignment: ", spam)

    do_nonlocal()
    print("After nonlocal assignment: ", spam)

    do_global()
    print("After global assignment: ", spam)

scope_test()
print("In global scope: ", spam)



#输出
After local assignment: test spam
After nonlocal assignment: nonlocal spam
After global assignment: nonlocal spam
In global scope: global spam

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class ClassName:
    <statement-1>
    .
    .
    .
    <statement-N>

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class MyClass:
    """A simple example class"""
    i = 12345

    def f(self):
        return 'hello world'

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#创建类的新实例，并将该对象分配给局部变量x
x = MyClass()

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def __init__(self):
    self.data = []

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class Complex:
    def __init__(self, realpart, imagpart):
        self.r = realpart
        self.i = imagpart


x = Complex(3.0, -4.5)
x.r, x.i
3.0, -4.5

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class Dog:

    kind = 'canine'         # class variable shared by all instances

    def __init__(self, name):
        self.name = name    # instance variable unique to each instance

>>> d = Dog('Fido')
>>> e = Dog('Buddy')
>>> d.kind                  # shared by all dogs
'canine'
>>> e.kind                  # shared by all dogs
'canine'
>>> d.name                  # unique to d
'Fido'
>>> e.name                  # unique to e
'Buddy'

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class Dog:

    tricks = []             # mistaken use of a class variable

    def __init__(self, name):
        self.name = name

    def add_trick(self, trick):
        self.tricks.append(trick)


>>> d = Dog('Fido')
>>> e = Dog('Buddy')
>>> d.add_trick('roll over')
>>> e.add_trick('play dead')
>>> d.tricks                # unexpectedly shared by all dogs
['roll over', 'play dead']

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class Dog:

    def __init__(self, name):
        self.name = name
        self.tricks = []    # creates a new empty list for each dog

    def add_trick(self, trick):
        self.tricks.append(trick)

>>> d = Dog('Fido')
>>> e = Dog('Buddy')
>>> d.add_trick('roll over')
>>> e.add_trick('play dead')
>>> d.tricks
['roll over']
>>> e.tricks
['play dead']

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# Function defined outside the class
def f1(self, x, y):
    return min(x, x+y)

class C:
    f = f1

    def g(self):
        return 'hello world'

    h = g


#f, g, h都是类C的所有属性，它们都是指向函数对象的，因此它们都是C实例的所有方法。

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class Bag:
    def __init__(self):
        self.data = []

    def add(self, x):
        self.data.append(x)

    def addtwice(self, x):
        self.add(x)
        self.add(x)

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#派生(derived)
class DerivedClassName(BaseClassName):
    <statement-1>
    .
    .
    .
    <statement-N>

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#当基类在另一个模块中被定义
class DerivedClassName(modname.BaseClassName):

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class DerivedClassName(Base1, Base2, Base3):
    <statement-1>
    .
    .
    .
    <statement-N>

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class Mapping:
    def __init__(self, iterable):
        self.items_list = []
        self.__update(iterable)

    def update(self, iterable):
        for item in iterable:
            self.items_list.append(item)

    __update = update   # private copy of original update() method

class MappingSubclass(Mapping):

    def update(self, keys, values):
        # provides new signature for update()
        # but does not break __init__()
        for item in zip(keys, values):
            self.items_list.append(item)

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class Employee:
    pass

john = Employee()  # Create an empty employee record

# Fill the fields of the record
john.name = 'John Doe'
john.dept = 'computer lab'
john.salary = 1000

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for element in [1, 2, 3]:
    print(element)
for element in (1, 2, 3):
    print(element)
for key in {'one':1, 'two':2}:
    print(key)
for char in "123":
    print(char)
for line in open("myfile.txt"):
    print(line, end='')

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>>> s = 'abc'
>>> it = iter(s)
>>> it
<iterator object at 0x00A1DB50>
>>> next(it)
'a'
>>> next(it)
'b'
>>> next(it)
'c'
>>> next(it)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
    next(it)
StopIteration

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class Reverse:
    """Iterator for looping over a sequence backwards."""
    def __init__(self, data):
        self.data = data
        self.index = len(data)

    def __iter__(self):
        return self

    def __next__(self):
        if self.index == 0:
            raise StopIteration
        self.index = self.index - 1
        return self.data[self.index]

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>>> rev = Reverse('spam')
>>> iter(rev)
<__main__.Reverse object at 0x00A1DB50>
>>> for char in rev:
...     print(char)
...
m
a
p
s

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def reverse(data):
    for index in range(len(data)-1, -1, -1):
        yield data[index]


>>> for char in reverse('golf'):
...     print(char)
...
f
l
o
g

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>>> sum(i*i for i in range(10))                 # sum of squares
285

>>> xvec = [10, 20, 30]
>>> yvec = [7, 5, 3]
>>> sum(x*y for x,y in zip(xvec, yvec))         # dot product
260

>>> from math import pi, sin
>>> sine_table = {x: sin(x*pi/180) for x in range(0, 91)}

>>> unique_words = set(word  for line in page  for word in line.split())

>>> valedictorian = max((student.gpa, student.name) for student in graduates)

>>> data = 'golf'
>>> list(data[i] for i in range(len(data)-1, -1, -1))
['f', 'l', 'o', 'g']

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#创建虚拟环境
python3 -m venv /tmp/pythonVenv

#激活
source /tmp/pythonVenv/bin/activate
(pythonVenv) [zhang@zhang21 ~]$

(pythonVenv) [zhang@zhang21 ~]$ python
>>> import sys
>>> sys.path
['', '/usr/lib64/python34.zip', '/usr/lib64/python3.4', '/usr/lib64/python3.4/plat-linux', '/usr/lib64/python3.4/lib-dynload', '/tmp/pythonVenv/lib64/python3.4/site-packages', '/tmp/pythonVenv/lib/python3.4/site-packages']


#退出
deactivate

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pip search sh

#默认安装最新版本
pip install sh

#安装指定版本
pip install sh=1.10.2

pip install --upgrade sh

pip uninstall sh

#显示已安装的模块的详细信息
pip show sh

#列出已安装模块
pip list


pip freeze > requirements.txt
#安装依赖
pip install -r ./requirements.txt

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# global

vim ~/.pip/pip.conf

# aliyun
[global]
trusted-host=mirrors.aliyun.com
index-url=https://mirrors.aliyun.com/pypi/simple/



# temporary
pip install xxx -i https://mirrors.aliyun.com/pypi/simple/

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>>> _
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name '_' is not defined
>>>
>>> 111
111
>>>
>>> _
111

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from django.utils.translation import ugettext as _
from django.http import HttpResponse

def my_view(request):
    output = _("Welcome to my site.")
    return HttpResponse(output)

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>>> def make_object(name, class):
SyntaxError: "invalid syntax"

>>> def make_object(name, class_):
...    pass

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class Abc:


    def __init__(self):
        pass

    def bcd(self):
        pass

def main():
    pass

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import os
import sys

from subprocess import Popen, PIPE

from abc.bcd import Xyz

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# 正确的模块名
import abc
import abc_def

# 不推荐的模块名
import Abc

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Class Abc():
    pass


Class _PrivateAbc(Abc):
    pass

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def abc():
    pass

def abc_def():
    pass
def _abc():
    pass

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name = 'abc'

MAX_CLIENT = 1000

1

# -*- coding: <encoding-name> -*-

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if 1900 < year < 2100 and 1 <= month <= 12 \
  and 1 <= day <= 31 and 0 <= hour < 24 \
  and 0 <= minute < 60 and 0 <= secod < 60:    #Look like a valid date
    return 1

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month_names = ['January', ‘February', 'March',    #comments
               'April', 'May', 'June',            #comments
			   'July', 'Auguest', 'September',    #comments
			   'October, 'November', 'December']