python cheatsheet,python-cheatsheet

缑勇锐

2023-12-01

Python标准库速查表

PS: README.md为最新文档！

使用Python v3.7.4制作

注意:

这里的每个代码片段都可以独立运行 (一些需要这个库提供的文件)

你可以使用GETREADME.py来从仓库中下载README.md(中英文，命令行前缀的有无皆可选择)

互联网数据: json

结构化标记: html

图形化用户界面: tkinter

string

Attributes

>>> import string

>>> string.ascii_letters

'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'

>>> string.ascii_lowercase

'abcdefghijklmnopqrstuvwxyz'

>>> string.ascii_uppercase

'ABCDEFGHIJKLMNOPQRSTUVWXYZ'

>>> string.digits

'0123456789'

>>> string.hexdigits

'0123456789abcdefABCDEF'

>>> string.octdigits

'01234567'

>>> string.punctuation

'!"#$%&\'()*+,-./:;<=>?@[\\]^_`{|}~'

>>> string.printable

'0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!"#$%&\'()*+,-./:;<=>?@[\\]^_`{|}~\t\n\r\x0b\x0c'

>>> string.whitespace

'\t\n\r\x0b\x0c'

Formatter

>>> import string

>>> formatter = string.Formatter()

>>> strcmp = "my name is {name}"

>>> dct = {"name": "nick"}

>>> formatter.format(strcmp, **dct)

'my name is nick'

>>> data = ("3")

>>> strcmp = "pi is about {}"

>>> formatter.format(strcmp, *data)

'pi is about 3'

Template

>>> import string

>>> strcmp = "Hello $World"

>>> t = string.Template(strcmp)

>>> t.substitute({"World": "nick"})

'Hello nick'

>>> t.substitute(World = "nick")

'Hello nick'

>>> class MyTemplate(string.Template):

... delimiter = "^"

...

>>> strcmp = "Hello ^World"

>>> mytemplate = MyTemplate(strcmp)

>>> mytemplate.substitute(World = "nick")

'Hello nick'

match, search, findall

>>> import re

>>> strcmp = "www.baidu.com"

>>> re.match("www", strcmp).span()

(0, 3)

>>> re.match("baidu", strcmp) # re.match only match from the beginning of the string

>>> re.search("baidu", strcmp).span() # re.search search from all string and return the first

(4, 9)

>>> strcmp = "baidu.com/runoob.com"

>>> re.findall("com", strcmp) # re.findall find all results and return

['com', 'com']

>>> re.findall("b(.*?).", strcmp)

['', '']

>>> re.findall("b(.*?)c", strcmp)

['aidu.', '.']

split, sub, escape

>>> import re

>>> re.split(r"\W", "hello,world")

['hello', 'world']

>>> re.sub(r"Boy|Girl", "Human", "boy and girl", flags = re.I) # re.I means ignoring apitalization

'Human and Human'

>>> re.escape(r"#$&*+-.^|~")

'\\#\\$\\&\\*\\+\\-\\.\\^\\|\\~'

difflib

Differ

>>> import difflib

>>> d = difflib.Differ()

>>> text1 = """difflib

... python version 3.7.4

... difflib version 3.7.4

... this is difflib document

... """

>>> text2 = """difflib

... python version 3.7.3

... this is difflib document

... feature: diff in linux

... """

>>> text1_lines = text1.splitlines()

>>> text2_lines = text2.splitlines()

>>>

>>> list(d.compare(text1_lines, text2_lines))

[' difflib', '- python version 3.7.4', '? ^\n', '+ python version 3.7.3', '? ^\n', '- difflib version 3.7.4', ' this is difflib document', '+ feature: diff in linux']

HtmlDiff

>>> import difflib

>>> d = difflib.HtmlDiff()

>>> text1 = """difflib

... python version 3.7.4

... difflib version 3.7.4

... this is difflib document

... """

>>> text2 = """difflib

... python version 3.7.3

... this is difflib document

... feature: diff in linux

... """

>>> text1_lines = text1.splitlines()

>>> text2_lines = text2.splitlines()

>>> with open("HtmlDiff.html", "w", encoding="utf-8") as f:

... HtmlDiff = d.make_file(text1_lines, text2_lines)

... f.write(HtmlDiff)

...

3331

SequenceMatcher

>>> import difflib

>>> s = difflib.SequenceMatcher(None, " abcd", "abcd abcd")

>>> s.find_longest_match(0, 5, 0, 9)

Match(a=0, b=4, size=5)

>>> s = difflib.SequenceMatcher(lambda x: x==" ", " abcd", "abcd abcd")

>>> s.find_longest_match(0, 5, 0, 9)

Match(a=1, b=0, size=4)

>>> s = difflib.SequenceMatcher(None, "abcd", "abd")

>>> s.get_matching_blocks()

[Match(a=0, b=0, size=2), Match(a=3, b=2, size=1), Match(a=4, b=3, size=0)]

textwrap

wrap, fill, shorten, dedent, indent

>>> import textwrap

>>> strcmp = "Hello,World! My name is nick, l am 14 years old"

>>> textwrap.wrap(strcmp, width = 10)

['Hello,Worl', 'd! My name', 'is nick, l', 'am 14', 'years old']

>>> textwrap.fill(strcmp, width = 10)

'Hello,Worl\nd! My name\nis nick, l\nam 14\nyears old'

>>> textwrap.shorten(strcmp, width = 45)

'Hello,World! My name is nick, l am 14 [...]'

>>> textwrap.shorten(strcmp, width = 45, placeholder = "...")

'Hello,World! My name is nick, l am 14...'

>>> strcmp = """

... hello world!

... """

>>> textwrap.dedent(strcmp)

'\nhello world!\n'

>>> strcmp = """Hello World!

... l am nick.

... l am 14 years old.

... """

>>> textwrap.indent(strcmp, " + ", lambda line: True)

' + Hello World!\n+ l am nick.\n+ l am 14 years old.\n'

unicodedata

lookup, name, unidata_version

>>> import unicodedata

>>> unicodedata.lookup('LEFT CURLY BRACKET')

'{'

>>> unicodedata.name("(")

'LEFT PARENTHESIS'

>>> unicodedata.unidata_version

'11.0.0'

codecs

encode, decode, getencoder, getdecoder

>>> import codecs

>>> codecs.encode("你好")

b'\xe4\xbd\xa0\xe5\xa5\xbd'

>>> codecs.decode(b"\xe4\xbd\xa0\xe5\xa5\xbd")

'你好'

>>> codecs.getencoder("utf-8")

>>> codecs.getdecoder("gbk")

struct

pack, unpack

>>> import struct

>>> struct.pack(">l", 1024)

b'\x00\x00\x04\x00'

>>> struct.unpack(">lH", b'\x00\x00\x04\x00\xf0\xf0')

(1024, 61680)

datetime

MINYEAR, MAXYEAR, date

>>> import datetime

>>> datetime.MINYEAR

>>> datetime.MAXYEAR

9999

>>> date = datetime.date

>>> date.today()

datetime.date(2019, 7, 21)

>>> date = datetime.date(2019, 7, 21)

>>> date.today()

datetime.date(2019, 7, 21)

>>> date.weekday()

>>> date.isocalendar()

(2019, 29, 7)

>>> date.ctime()

'Sun Jul 21 00:00:00 2019'

>>> date.strftime("%Y %d %y, %H:%M:%S")

'2019 21 19, 00:00:00'

calendar

isleap, firstweekday, month

>>> import calendar

>>> calendar.isleap(2000)

True

>>> calendar.firstweekday()

>>> print(calendar.month(2019, 7))

July 2019

Mo Tu We Th Fr Sa Su

1 2 3 4 5 6 7

8 9 10 11 12 13 14

15 16 17 18 19 20 21

22 23 24 25 26 27 28

29 30 31

collections

namedtuple, deque, defaultdict, OrderedDict, Counter

>>> import collections

>>> point = collections.namedtuple("point", ["x", "y"])

>>> p = point(2, 1)

>>> p.x, p.y

(2, 1)

>>> deque = collections.deque(["b", "c", "d"])

>>> deque.appendleft("a")

>>> deque.append("e")

>>> deque

deque(['a', 'b', 'c', 'd', 'e'])

>>> dd = collections.defaultdict(lambda: "None")

>>> dd ["key-1"] = "value-1"

>>> dd["key-1"]

'value-1'

>>> dd["key-2"]

'None'

>>> od = collections.OrderedDict([("a", 1), ("b", 2)])

>>> od

OrderedDict([('a', 1), ('b', 2)])

>>> c = collections.Counter()

>>> for i in "Hello, World":

... c[i] = c[i] + 1

...

>>> c

Counter({'l': 3, 'o': 2, 'H': 1, 'e': 1, ',': 1, ' ': 1, 'W': 1, 'r': 1, 'd': 1})

copy

copy, deepcopy

>>> import copy

>>> origin = [1, 2, [3, 4]]

>>> copy1 = copy.copy(origin)

>>> copy2 = copy.deepcopy(origin)

>>> copy1 is copy2

False

>>> origin[2][0] = "Hello, copy"

>>> copy1

[1, 2, ['Hello, copy', 4]]

>>> copy2

[1, 2, [3, 4]]

pprint

>>> import pprint

>>> strcmp = ("hello world", {"nick": 13, "ben": 12}, (1, 2, 3, 4), [5, 6, 7, 8], "Hello pprint")

>>> pprint.pprint(strcmp)

('hello world',

{'ben': 12, 'nick': 13},

(1, 2, 3, 4),

[5, 6, 7, 8],

'Hello pprint')

enum

Enum, unique, auto

>>> import enum

>>> class Seasons(enum.Enum):

... Spring = 1

... Summer = 2

... Autumn = 3

... Winter = 4

...

>>> Seasons.Spring

>>> @enum.unique

... class Unique(enum.Enum):

... Nick = 13

... Ben = 12

... Jack = 13

...

Traceback (most recent call last):

File "", line 2, in

File "C:\Python38\lib\enum.py", line 860, in unique

raise ValueError('duplicate values found in %r: %s' %

ValueError: duplicate values found in : Jack -> Nick

>>> class Auto(enum.Enum):

... VS = enum.auto()

... VSCode = enum.auto()

... Pycharm = enum.auto()

...

>>> list(Auto)

[, , ]

bisect

bisect, bisect_left, bisect_right, insort, insort_left, insort_right

>>> import bisect

>>> a = [1, 2, 4, 5]

>>> bisect.bisect_left(a, 1)

>>> bisect.bisect_right(a, 1)

>>> bisect.bisect(a, 1)

>>> bisect.insort(a, 1)

>>> a

[1, 1, 2, 4, 5]

>>> bisect.insort_left(a, 2)

>>> a

[1, 1, 2, 2, 4, 5]

>>> bisect.insort_right(a, 4)

>>> a

[1, 1, 2, 2, 4, 4, 5]

heapq

heappush, heappop

>>> import heapq

>>> def heapsort(iterable):

... h = []

... for i in iterable:

... heapq.heappush(h, i)

... return [heapq.heappop(h) for i in range(len(h))]

...

>>> heapsort([4, 3, 6, 9, 1, 7])

[1, 3, 4, 6, 7, 9]

weakref

ref

>>> import weakref

>>> class A:

... def method():

... print("A")

...

>>> def b(reference):

... print(reference)

...

>>> c = A()

>>> d = weakref.ref(c, b)

>>> del c

math

ceil, factorial, floor, modf, log, pow, sqrt, pi, e

>>> import math

>>> math.ceil(1.4)

>>> math.factorial(5)

120

>>> math.floor(1.6)

>>> math.modf(1.6)

(0.6000000000000001, 1.0)

>>> math.log(8)

2.0794415416798357

>>> math.pow(2,5)

32.0

>>> math.sqrt(9)

3.0

>>> math.pi

3.141592653589793

>>> math.e

2.718281828459045

cmath

sin, tan, cos

>>> import cmath

>>> cmath.sin(7)

(0.6569865987187891+0j)

>>> cmath.tan(7)

(0.8714479827243188+0j)

>>> cmath.cos(7)

(0.7539022543433046-0j)

random

random, uniform, randint, randrange

>>> import random

>>> random.random()

0.6381052887323486

>>> random.uniform(5,6)

5.325285695528384

>>> random.randint(6, 9)

>>> random.randrange(5, 10)

fractions

Fraction, limit_denominator

>>> import fractions

>>> fractions.Fraction(16, -10)

Fraction(-8, 5)

>>> fractions.Fraction("-16/10")

Fraction(-8, 5)

>>> fractions.Fraction(8, 5) - fractions.Fraction(7, 5)

Fraction(1, 5)

>>> fractions.Fraction(1.1)

Fraction(2476979795053773, 2251799813685248)

>>> fractions.Fraction(1.1).limit_denominator()

Fraction(11, 10)

>>> import math

>>> math.floor(fractions.Fraction(5, 3))

decimal

Decimal, getcontext

>>> import decimal

>>> decimal.Decimal(2)/decimal.Decimal(3)

Decimal('0.6666666666666666666666666667')

>>> context = decimal.getcontext()

>>> context

Context(prec=28, rounding=ROUND_HALF_EVEN, Emin=-999999, Emax=999999, capitals=1, clamp=0, flags=[Inexact, Rounded], traps=[InvalidOperation, DivisionByZero, Overflow])

>>> context.prec = 5

>>> x = decimal.Decimal(2)/decimal.Decimal(3)

>>> x

Decimal('0.66667')

>>> x.sqrt()

Decimal('0.81650')

>>> x.log10()

Decimal('-0.17609')

statistics

mean, harmonic_mean, median, median_low, median_high

>>> import statistics

>>> statistics.mean([1, 2, 3])

>>> statistics.harmonic_mean([2, 5, 10])

3.75

>>> statistics.median([2, 3, 5, 6])

4.0

>>> statistics.median_low([2, 3, 5, 6])

>>> statistics.median_high([2, 3, 5, 6])

itertools

count, repeat, groupby

>>> import itertools # itertools always return a iterator

>>> for i in zip(itertools.count(1), ["A", "B", "C"]):

... print(i)

...

(1, 'A')

(2, 'B')

(3, 'C')

>>> for i in itertools.repeat("Hello Repeat!", 5):

... print(i)

...

Hello Repeat!

>>> [list(g) for k, g in itertools.groupby('AAAABBBCCD')]

[['A', 'A', 'A', 'A'], ['B', 'B', 'B'], ['C', 'C'], ['D']]

functools

lru_cache, reduce

>>> import functools

>>> @functools.lru_cache(None) # None means the cache's upper limit is not limited

... def fibonacci(n):

... if n<2:

... return n

... return fibonacci(n-1) + fibonacci(n-2)

...

>>> fibonacci(10)

>>> def add(a, b):

... return a+b

...

>>> functools.reduce(add, range(1,100))

4950

operator

lt, eq, le, ne, gt, ge, abs, pow, concat, contains, indexOf, add

>>> import operator

>>> operator.lt(3, 4) # 3<4

True

>>> operator.eq(3, 4) # 3=4

False

>>> operator.le(3, 4) # 3<=4

True

>>> operator.ne(3, 4) # 3!=4

True

>>> operator.gt(3, 4) # 3>4

False

>>> operator.ge(3, 4) # 3>=4

False

>>> operator.abs(-10)

>>> operator.pow(10, 2)

100

>>> operator.concat("a", "b")

'ab'

>>> operator.contains([1, 2, 3], 2)

True

>>> operator.indexOf([1, 2, 3, 2, 1], 2)

>>> operator.add(1, 2)

pathlib

Path

>>> import pathlib

>>> p = pathlib.Path(".")

>>> list(p.glob('**/*.py'))

[WindowsPath('GETREADME.py'), WindowsPath('test.py')]

>>> p/"dir"

WindowsPath('dir')

>>> (p/"GETREADME.py").name

'GETREADME.py'

>>> p.is_absolute()

False

os.path

exists, getsize, isfile, isdir, join

>>> import os.path

>>> os.path.exists(".")

True

>>> os.path.getsize("./LICENSE")

466

>>> os.path.isfile("./README.md")

True

>>> os.path.isdir("./doc")

False

>>> os.path.join("./doc", "tutorial", "basic")

'./doc\\tutorial\\basic'

glob

>>> import glob

>>> glob.glob("*.md", recursive = True)

['python-cheatsheet.md', 'README-zh-cn.md', 'README.md']

tempfile

TemporaryFile, mkstemp, mkdtemp

>>> import tempfile

>>> with tempfile.TemporaryFile() as f:

f.write(b"Hello tempfile")

f.seek(0)

f.read()

b'Hello tempfile'

>>> name = tempfile.mkstemp() # for temporary file

>>> name

(3, 'C:\\Users\\ADMINI~1\\AppData\\Local\\Temp\\tmp___ejm5a')

>>> with open(name[1], "w", encoding="utf-8") as f:

f.write("Hello tempfile!")

>>> name = tempfile.mkdtemp() # for temporary dir

>>> name

'C:\\Users\\ADMINI~1\\AppData\\Local\\Temp\\tmp5mqb0bxz'

>>> with open(name + "\\temp.txt", "w", encoding="utf-8") as f:

f.write("Hello tempfile!")

filecmp

cmp

>>> import filecmp

>>> filecmp.cmp("cmp1.txt", "cmp2.txt")

True

fileinput

input

>>> import os

>>> cmd = os.popen("python fileinput_example.py cmp1.txt")

>>> print(cmd.read())

cmp1.txt | Line Number: 1 |: 1

cmp1.txt | Line Number: 2 |: 2

cmp1.txt | Line Number: 3 |: 3

cmp1.txt | Line Number: 4 |: 4

cmp1.txt | Line Number: 5 |: 5

shutil

copyfile, rmtree, move

>>> import shutil

>>> shutil.copyfile("song.wav", "copysong.wav")

'copysong.wav'

>>> shutil.rmtree("shutil_tree")

>>> shutil.move("copysong.wav", "myapp/copysong.wav")

'myapp/copysong.wav'

pickle

loads, dumps

>>> import pickle

>>> data = [[1, "first"],

... [2, "second"]]

>>> dumps = pickle.dumps(data)

>>> dumps

b'\x80\x03]q\x00(]q\x01(K\x01X\x05\x00\x00\x00firstq\x02e]q\x03(K\x02X\x06\x00\x00\x00secondq\x04ee.'

>>> pickle.loads(dumps)

[[1, 'first'], [2, 'second']]

copyreg

pickle

>>> import copyreg

>>> import copy

>>> import pickle

>>> class A:

... def __init__(self, a):

... self.a = a

...

>>> def pickle_a(a):

... print("pickle A")

... return A, (a.a,)

...

>>> copyreg.pickle(A, pickle_a)

>>> a = A(1)

>>> b = copy.copy(a)

pickle A

>>>

>>> c = pickle.dumps(a)

pickle A

zlib

compress, decompress

>>> import zlib

>>> zlib.compress(b"Hello World!", 5)

b'x^\xf3H\xcd\xc9\xc9W\x08\xcf/\xcaIQ\x04\x00\x1cI\x04>'

>>> zlib.decompress(b'x^\xf3H\xcd\xc9\xc9W\x08\xcf/\xcaIQ\x04\x00\x1cI\x04>')

b'Hello World!'

lzma

compress, decompress

>>> import lzma

>>> lzma.compress(b"Hello, python3!")

b"\xfd7zXZ\x00\x00\x04\xe6\xd6\xb4F\x02\x00!\x01\x16\x00\x00\x00t/\xe5\xa3\x01\x00\x0eHello, python3!\x00\x00(\x92K\xe6\x9b\xe7r&\x00\x01'\x0f\xdf\x1a\xfcj\x1f\xb6\xf3}\x01\x00\x00\x00\x00\x04YZ"

>>> lzma.decompress(b"\xfd7zXZ\x00\x00\x04\xe6\xd6\xb4F\x02\x00!\x01\x16\x00\x00\x00t/\xe5\xa3\x01\x00\x0eHello, python3!\x00\x00(\x92K\xe6\x9b\xe7r&\x00\x01'\x0f\xdf\x1a\xfcj\x1f\xb6\xf3}\x01\x00\x00\x00\x00\x04YZ")

b'Hello, python3!'

zipfile

ZipFile

>>> import zipfile

>>> with zipfile.ZipFile("README.zip") as f:

... f.extractall()

...

>>> with zipfile.ZipFile("LICENSE.zip", "a") as zip:

... zip.write("LICENSE")

...

configparser

ConfigParser

>>> import configparser

>>> config = configparser.ConfigParser()

>>> config.read("config.ini")

['config.ini']

>>> config.sections()

['python', 'java']

>>> config["python"]["type"]

'programming language'

>>> config["java"]["popular"]

'1'

hashlib

md5

>>> import hashlib

>>> md5 = hashlib.md5()

>>> md5.update(b"Hello World")

>>> md5.block_size

>>> md5.digest_size

>>> md5.hexdigest()

'b10a8db164e0754105b7a99be72e3fe5'

>>> md5.digest()

b'\xb1\n\x8d\xb1d\xe0uA\x05\xb7\xa9\x9b\xe7.?\xe5'

hmac

new, compare_digest

>>> import hmac

>>> msg = b"Hello World"

>>> secret = b"key"

>>> h = hmac.new(secret, msg, digestmod='md5')

>>> h.hexdigest()

'432c3ea3b9a503183f3d1258d9016a0c'

>>> h.digest()

b'C,>\xa3\xb9\xa5\x03\x18?=\x12X\xd9\x01j\x0c'

>>> h2 = hmac.new(secret, b"Hello world", digestmod="md5")

>>> hmac.compare_digest(h.digest(), h2.digest())

False

secrets

choice, token_bytes, token_hex

>>> import secrets

>>> secrets.choice("Hello World!")

'd'

>>> secrets.token_bytes(32)

b'\xd7\x98\xba\xc5\x18[/\xeaLx\xdb\x962\x84\xff`(7&\xe6\xae\xd4\x17n,\xc3\x9e\xb0V\x1c\x1d\x99'

>>> secrets.token_hex(16)

'335f8df0cb6dd60a3c41fdba7ccd1a0b'

name, getcwd

>>> import os

>>> os.name

'nt'

>>> os.getcwd()

'C:\\Users\\Nick'

time

localtime, ctime, perf_counter, sleep, strftime

>>> import time

>>> time.localtime()

time.struct_time(tm_year=2019, tm_mon=7, tm_mday=29, tm_hour=12, tm_min=18, tm_sec=57, tm_wday=0, tm_yday=210, tm_isdst=0)

>>> time.ctime()

'Mon Jul 29 12:19:40 2019'

>>> time.perf_counter()

174.1987535

>>> time.sleep(1)

>>> time.strftime("%d %b %Y")

'29 Jul 2019'

logging

log, info, debug, warning, error, critical

>>> import logging

>>> logging.basicConfig(level = logging.INFO,format = '%(asctime)s - %(name)s - %(levelname)s - %(message)s')

>>> logger = logging.getLogger(__name__)

>>> logger.info("info")

2019-07-29 12:29:59,363 - __main__ - INFO - info

>>> logger.debug("debug")

>>> logger.error("error")

2019-07-29 12:30:26,729 - __main__ - ERROR - error

>>> logger.critical("critical")

2019-07-29 12:30:36,446 - __main__ - CRITICAL - critical

>>> logger.warning("warning")

2019-07-29 12:30:48,815 - __main__ - WARNING - warning

>>> logger.log(35, "log")

2019-07-29 12:31:59,758 - __main__ - Level 35 - log

getpass

getpass, getuser

>>> import getpass

>>> password = getpass.getpass()

Password:

>>> password

'xxx'

>>> getpass.getuser()

'Nick'

platform

machine, platform, python_compiler, python_version, system

>>> import platform

>>> platform.machine()

'AMD64'

>>> platform.platform()

'Windows-10-10.0.18362-SP0'

>>> platform.python_compiler()

'MSC v.1916 64 bit (AMD64)'

>>> platform.python_version()

'3.7.4'

>>> platform.system()

'Windows'

argparse

ArgumentParser

>>> import os

>>> def cmd(command):

... res = os.popen(command)

... print(res.read())

...

>>> cmd("python argparse_example.py -a 1 -b 2 --sum 1 2 3 4 -r 10 -t")

Namespace(a=1, b=2, required='10', sum=[1, 2, 3, 4], true=True)

>>> cmd("python argparse_example.py --help")

usage: argparse_example.py [-h] [-a A] [-b B] [-s SUM [SUM ...]] -r REQUIRED

[-t]

the example parser for argparse

optional arguments:

-h, --help show this help message and exit

-a A the a number for adding

-b B the b number for adding

-s SUM [SUM ...], --sum SUM [SUM ...]

-r REQUIRED, --required REQUIRED

-t, --true

errno

errorcode

>>> import errno

>>> errno.errorcode

{19: 'ENODEV', 10065: 'WSAEHOSTUNREACH', 122: 'ENOMSG', 120: 'ENODATA', 40: 'ENOSYS', 32: 'EPIPE', 22: 'EINVAL', 132: 'EOVERFLOW', 4: 'EINTR', 10068: 'WSAEUSERS', 41: 'ENOTEMPTY', 10055: 'WSAENOBUFS', 134: 'EPROTO', 10071: 'WSAEREMOTE', 10: 'ECHILD', 10062: 'WSAELOOP', 18: 'EXDEV', 7: 'E2BIG', 3: 'ESRCH', 10040: 'WSAEMSGSIZE', 10047: 'WSAEAFNOSUPPORT', 10064: 'WSAEHOSTDOWN', 10046: 'WSAEPFNOSUPPORT', 10042: 'WSAENOPROTOOPT', 16: 'EBUSY', 10035: 'WSAEWOULDBLOCK', 10056: 'WSAEISCONN', 10058: 'WSAESHUTDOWN', 9: 'EBADF', 5: 'EIO', 10041: 'WSAEPROTOTYPE', 28: 'ENOSPC', 8: 'ENOEXEC', 10037: 'WSAEALREADY', 10050: 'WSAENETDOWN', 13: 'EACCES', 42: 'EILSEQ', 20: 'ENOTDIR', 1: 'EPERM', 33: 'EDOM', 10061: 'WSAECONNREFUSED', 21: 'EISDIR', 10043: 'WSAEPROTONOSUPPORT', 30: 'EROFS', 10049: 'WSAEADDRNOTAVAIL', 111: 'EIDRM', 104: 'EBADMSG', 23: 'ENFILE', 29: 'ESPIPE', 121: 'ENOLINK', 10052: 'WSAENETRESET', 10060: 'WSAETIMEDOUT', 2: 'ENOENT', 17: 'EEXIST', 10069: 'WSAEDQUOT', 125: 'ENOSTR', 14: 'EFAULT', 27: 'EFBIG', 36: 'EDEADLOCK', 10057: 'WSAENOTCONN', 10039: 'WSAEDESTADDRREQ', 39: 'ENOLCK', 10053: 'WSAECONNABORTED', 10051: 'WSAENETUNREACH', 10070: 'WSAESTALE', 124: 'ENOSR', 12: 'ENOMEM', 10038: 'WSAENOTSOCK', 31: 'EMLINK', 34: 'ERANGE', 10054: 'WSAECONNRESET', 10048: 'WSAEADDRINUSE', 10045: 'WSAEOPNOTSUPP', 11: 'EAGAIN', 38: 'ENAMETOOLONG', 25: 'ENOTTY', 10044: 'WSAESOCKTNOSUPPORT', 137: 'ETIME', 10059: 'WSAETOOMANYREFS', 24: 'EMFILE', 139: 'ETXTBSY', 10036: 'WSAEINPROGRESS', 6: 'ENXIO', 10024: 'WSAEMFILE', 10092: 'WSAVERNOTSUPPORTED', 10067: 'WSAEPROCLIM', 10014: 'WSAEFAULT', 10093: 'WSANOTINITIALISED', 10063: 'WSAENAMETOOLONG', 10066: 'WSAENOTEMPTY', 10013: 'WSAEACCES', 10000: 'WSABASEERR', 10009: 'WSAEBADF', 10101: 'WSAEDISCON', 10004: 'WSAEINTR', 10091: 'WSASYSNOTREADY', 10022: 'WSAEINVAL', 105: 'ECANCELED', 133: 'EOWNERDEAD', 127: 'ENOTRECOVERABLE', 129: 'ENOTSUP'}

StringIO, BytesIO

>>> import io

>>> stringio = io.StringIO()

>>> stringio.write("Hello World!")

>>> stringio.seek(6)

>>> stringio.read()

'World!'

>>> stringio.close()

>>> bytesio = io.BytesIO()

>>> bytesio.write(b"Hello World")

>>> bytesio.seek(0)

>>> bytesio.read()

b'Hello World'

>>> bytesio.close()

socket

Run in bash:

python socker_server.py

Connected by ('127.0.0.1', 64346)

python socket_client.py

Received b'Hello, world'

json

dumps, loads

>>> import json

>>> x = json.dumps({"Nick": 13, "Ben": 10})

>>> x

'{"Nick": 13, "Ben": 10}'

>>> json.loads(x)

{'Nick': 13, 'Ben': 10}

html

escape, unescape

>>> import html

>>> html.escape("As we all know, 2>1")

'As we all know, 2>1'

>>> html.unescape('As we all know, 2>1')

'As we all know, 2>1'

webbrowser

open, open_new, open_new_tab

>>> import webbrowser

>>> webbrowser.open("www.baidu.com")

True

>>> webbrowser.open_new("www.baidu.com")

True

>>> webbrowser.open_new_tab("www.baidu.com")

True

wave

open

>>> import wave

>>> f = wave.open("song.wav", "rb")

>>> f.getparams()

_wave_params(nchannels=2, sampwidth=2, framerate=44100, nframes=442368, comptype='NONE', compname='not compressed')

sndhdr

what

>>> import sndhdr

>>> sndhdr.what("song.wav")

SndHeaders(filetype='wav', framerate=44100, nchannels=2, nframes=442368, sampwidth=16)

imghdr

what

>>> import imghdr

>>> imghdr.what("china.jpg")

'jpeg'

colorsys

rgb_to_yiq, rgb_to_hls, rgb_to_hsv

>>> import colorsys

>>> colorsys.rgb_to_yiq(128, 128, 0)

(113.91999999999999, 41.177600000000005, -39.948799999999984)

>>> colorsys.rgb_to_hls(128, 128, 0)

(0.16666666666666666, 64.0, -1.0158730158730158)

>>> colorsys.rgb_to_hsv(128, 128, 0)

(0.16666666666666666, 1.0, 128)

turtle

pensize, pencolor, begin_fill, forward, right, end_fill

>>> import turtle

>>> turtle.pensize(5)

>>> turtle.pencolor("yellow")

>>> turtle.begin_fill()

>>> for _ in range(5):

... turtle.forward(200)

... turtle.right(144)

...

>>> turtle.end_fill()

tkinter

Tk, Label

run in bash:

python tkinter_example.py

typing

List, NewType

>>> import typing

>>> lst = typing.List[int]

>>> float_lst = typing.List[float]

>>> def foo(x: float, lst: lst)->float_lst:

... return [x*num for num in lst]

...

>>> foo(1.5, [3, 4, 5])

[4.5, 6.0, 7.5]

>>> ID = typing.NewType("ID", int)

>>> ID(70)

doctest

testfile

>>> import doctest

>>> doctest.testfile("doctest_example.txt", verbose=True)

Trying:

from doctest_example import factorial

Expecting nothing

Trying:

[factorial(n) for n in range(6)]

Expecting:

[1, 1, 2, 6, 24, 120]

Trying:

factorial(30)

Expecting:

265252859812191058636308480000000

1 items passed all tests:

3 tests in doctest_example.txt

3 tests in 1 items.

3 passed and 0 failed.

Test passed.

TestResults(failed=0, attempted=3)

timeit

timeit, Timer

>>> import timeit

>>> timeit.timeit("[i for i in range(10000)]", number = 1000)

1.0810747999999961

>>> timeit.timeit("lst = []\nfor i in range(10000):\nlst.append(i)", number = 1000)

1.770644500000003

>>> a = timeit.Timer("[i for i in range(10000)]")

>>> a.timeit(number = 1000)

0.9840328999999883

pdb

set_trace

>>> import pdb

>>> def foo():

... lst = []

... for i in range(2):

... pdb.set_trace()

... lst.append(i)

... return lst

...

>>> foo()

> (5)foo()

(Pdb) p i

(Pdb) p lst

[]

(Pdb) n

> (3)foo()

(Pdb) list

[EOF]

(Pdb) n

> (4)foo()

(Pdb) r

> (5)foo()

(Pdb) p i

(Pdb) p lst

[0]

(Pdb) q

Traceback (most recent call last):

File "", line 1, in

File "", line 5, in foo

File "C:\Python37\lib\bdb.py", line 88, in trace_dispatch

return self.dispatch_line(frame)

File "C:\Python37\lib\bdb.py", line 113, in dispatch_line

if self.quitting: raise BdbQuit

bdb.BdbQuit

ensurepip

version, bootstrap

>>> import ensurepip

>>> ensurepip.version()

'19.0.3'

>>> ensurepip.bootstrap(upgrade=True)

Looking in links: C:\Users\Nick\AppData\Local\Temp\tmpus54fm12

Requirement already up-to-date: setuptools in c:\python37\lib\site-packages (41.2.0)

Requirement already up-to-date: pip in c:\python37\lib\site-packages (19.2.3)

Run in bash:

python -m ensurepip # download pip

python -m ensurepip --upgrade # upgrade pip

zipapp

create_archive

>>> import zipapp

>>> zipapp.create_archive("myapp", "myapp.pyz", main="app:main")

>>> __import__("os").popen("python myapp.pyz").read()

'Hello, zipapp!\n'

sys

exc_info, implementation, maxsize, platform, version

>>> import sys

>>> try:

... 1/0

... except Exception:

... print(sys.exc_info()) # traceback.print_exc is a beautful version of sys.exc_info()

...

(, ZeroDivisionError('division by zero'), )

>>> sys.implementation

namespace(cache_tag='cpython-37', hexversion=50791664, name='cpython', version=sys.version_info(major=3, minor=7, micro=4, releaselevel='final', serial=0))

>>> sys.maxsize

9223372036854775807

>>> sys.platform

'win32'

>>> sys.version

'3.7.4 (tags/v3.7.4:e09359112e, Jul 8 2019, 20:34:20) [MSC v.1916 64 bit (AMD64)]'

>>> sys.exit()

dataclasses

dataclass

>>> import dataclasses

>>> @dataclasses.dataclass

... class User:

... name: str

... age: int

... def get_info(self):

... return self.name + " is " + str(self.age) + " years old."

...

>>> pynickle = User("pynickle", 14)

>>> pynickle.get_info()

'pynickle is 14 years old.'

contextlib

contextmanager

>>> import contextlib

>>> @contextlib.contextmanager

... def cm(name):

... print("__enter__ cm")

... yield "Hello," + name

... print("__exit__ cm")

...

>>> with cm("pynickle") as value:

... print(value)

...

__enter__ cm

Hello,pynickle

__exit__ cm

>>> with cm("pynickle") as a, cm("bob") as b:

... print(a, b)

...

__enter__ cm

Hello,pynickle Hello,bob

__exit__ cm

abc

ABCMeta, abstractmethod

>>> import abc

>>> class User(metaclass=abc.ABCMeta):

... def hello(self, name):

... print("Hello," + name)

... @abc.abstractmethod

... def unique_hello(self):

... self.hello()

... @property

... @abc.abstractmethod

... def age():

... pass

...

>>> class UserOne(User):

... def unique_hello(self):

... self.hello()

... print("l am coming!")

... def age():

... return "13"

...

>>> user1 = UserOne()

>>> dir(user1)

['__abstractmethods__', '__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__', '_abc_impl', 'age', 'hello', 'unique_hello']

>>> isinstance(user1, User)

True

>>> class UserTwo():

... pass

...

>>> User.register(UserTwo) # register only made UserTwo subclass of Uuser, but none of the methods

>>> user2 = UserTwo()

>>> dir(user2)

['__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__']

>>> issubclass(UserTwo, User)

True

traceback

print_exc

>>> import traceback

>>> try:

... 1/0

... except Exception:

... traceback.print_exc()

...

Traceback (most recent call last):

File "", line 2, in

ZeroDivisionError: division by zero

future

division, absolute_import, print_function, unicode_literals

>>> from __future__ import division, absolute_import, print_function, unicode_literals

atexit

>>> import atexit

>>> def bye():

... print("bye!")

...

>>> atexit.register(bye)

>>> exit()

bye!

builtins

range

>>> import builtins

>>> for i in builtins.range(10):

... print(i)

...

inspect

getmembers, ismethod, isfunction, isclass, isbuiltin

>>> import inspect

>>> inspect.getmembers([1, 2, 3])

[('__add__', ), ('__class__', ), ('__contains__', ), ('__delattr__', ), ('__delitem__', ), ('__dir__', ), ('__doc__', 'Built-in mutable sequence.\n\nIf no argument is given, the constructor creates a new empty list.\nThe argument must be an iterable if specified.'), ('__eq__', ), ('__format__', ), ('__ge__', ), ('__getattribute__', ), ('__getitem__', ), ('__gt__', ), ('__hash__', None), ('__iadd__', ), ('__imul__', ), ('__init__', ), ('__init_subclass__', ), ('__iter__', ), ('__le__', ), ('__len__', ), ('__lt__', ), ('__mul__', ), ('__ne__', ), ('__new__', ), ('__reduce__', ), ('__reduce_ex__', ), ('__repr__', ), ('__reversed__', ), ('__rmul__', ), ('__setattr__', ), ('__setitem__', ), ('__sizeof__', ), ('__str__', ), ('__subclasshook__', ), ('append', ), ('clear', ), ('copy', ), ('count', ), ('extend', ), ('index', ), ('insert', ), ('pop', ), ('remove', ), ('reverse', ), ('sort', )]

>>> print(inspect.getdoc([1, 2, 3]))

Built-in mutable sequence.

If no argument is given, the constructor creates a new empty list.

The argument must be an iterable if specified.

>>> inspect.ismethod(inspect.getmembers)

False

>>> inspect.isbuiltin(repr)

True

>>> inspect.isfunction(lambda x:x+1)

True

>>> inspect.isclass(inspect.Signature)

True

zipimport

importer

>>> import zipimport

>>> zip = zipimport.zipimporter("GETREADME.zip")

>>> zip.archive

'GETREADME.zip'

>>>

>>> getreadme = zip.load_module("GETREADME")

>>> getreadme

>>> getreadme.main(0)

Requesting...

Processing...

Saving...

Using: 0.98 s

importlib

import, reload

>>> import importlib

>>> sys = importlib.__import__("sys") # equal to built in function __import__

>>> importlib.reload(sys)

runpy

run_module, run_path

>>> runpy.run_module("app")

{'__name__': 'app', '__file__': 'C:\\Users\\Nick\\Desktop\\my-github\\python-cheatsheet\\app.py', '__cached__': 'C:\\Users\\Nick\\Desktop\\my-github\\python-cheatsheet\\__pycache__\\app.cpython-37.pyc', '__doc__': None, '__loader__': <_frozen_importlib_external.sourcefileloader object at>, '__package__': '', '__spec__': ModuleSpec(name='app', loader=<_frozen_importlib_external.sourcefileloader object at>, origin='C:\\Users\\Nick\\Desktop\\my-github\\python-cheatsheet\\app.py'), '__builtins__': {'__name__': 'builtins', '__doc__': "Built-in functions, exceptions, and other objects.\n\nNoteworthy: None is the `nil' object; Ellipsis represents `...' in slices.", '__package__': '', '__loader__': , '__spec__': ModuleSpec(name='builtins', loader=), '__build_class__': , '__import__': , 'abs': , 'all': , 'any': , 'ascii': , 'bin': , 'breakpoint': , 'callable': , 'chr': , 'compile': , 'delattr': , 'dir': , 'divmod': , 'eval': , 'exec': , 'format':

function format>, 'getattr': , 'globals': , 'hasattr': , 'hash': , 'hex': , 'id': , 'input': , 'isinstance': , 'issubclass': , 'iter': , 'len': , 'locals': , 'max': , 'min': , 'next': , 'oct': , 'ord': , 'pow': , 'print': , 'repr': , 'round': , 'setattr': , 'sorted': , 'sum': , 'vars': , 'None': None, 'Ellipsis': Ellipsis, 'NotImplemented': NotImplemented, 'False': False, 'True': True, 'bool': , 'memoryview': , 'bytearray': , 'bytes': , 'classmethod': , 'complex': , 'dict': , 'enumerate': , 'filter': , 'float': , 'frozenset': , 'property': , 'int': , 'list': , 'map': , 'object': , 'range': , 'reversed': , 'set': , 'slice': , 'staticmethod': , 'str':

, 'super': , 'tuple': , 'type': , 'zip': , '__debug__': True, 'BaseException': , 'Exception': , 'TypeError': , 'StopAsyncIteration': , 'StopIteration': , 'GeneratorExit': , 'SystemExit': , 'KeyboardInterrupt': , 'ImportError': , 'ModuleNotFoundError': , 'OSError': , 'EnvironmentError': ,

'IOError': , 'WindowsError': , 'EOFError': , 'RuntimeError': , 'RecursionError': , 'NotImplementedError': , 'NameError': , 'UnboundLocalError': , 'AttributeError': , 'SyntaxError': , 'IndentationError': , 'TabError': , 'LookupError': , 'IndexError': , 'KeyError': , 'ValueError': , 'UnicodeError': , 'UnicodeEncodeError': , 'UnicodeDecodeError': , 'UnicodeTranslateError': , 'AssertionError': , 'ArithmeticError': , 'FloatingPointError': , 'OverflowError': , 'ZeroDivisionError': , 'SystemError': , 'ReferenceError': , 'MemoryError': , 'BufferError': , 'Warning': , 'UserWarning': , 'DeprecationWarning': , 'PendingDeprecationWarning': , 'SyntaxWarning': , 'RuntimeWarning': , 'FutureWarning': , 'ImportWarning': , 'UnicodeWarning': , 'BytesWarning': , 'ResourceWarning': , 'ConnectionError': , 'BlockingIOError': , 'BrokenPipeError': , 'ChildProcessError': , 'ConnectionAbortedError': , 'ConnectionRefusedError': , 'ConnectionResetError': , 'FileExistsError': , 'FileNotFoundError': , 'IsADirectoryError': , 'NotADirectoryError': , 'InterruptedError': , 'PermissionError': , 'ProcessLookupError': , 'TimeoutError': , 'open': , 'quit': Use quit() or Ctrl-Z plus Return to exit, 'exit': Use exit() or Ctrl-Z plus Return to exit, 'copyright': Copyright (c) 2001-2019 Python Software Foundation.

for supporting Python development. See www.python.org for more information., 'license': Type license() to see the full license text, 'help': Type help() for interactive help, or help(object) for help about object., '_': None}}

>>> runpy.run_path("myapp")

Hello, runpy!

{'__name__': '', '__doc__': None, '__package__': '', '__loader__': <_frozen_importlib_external.sourcefileloader object at>, '__spec__': ModuleSpec(name='__main__', loader=<_frozen_importlib_external.sourcefileloader object at>, origin='myapp\\__main__.py'), '__file__': 'myapp\\__main__.py', '__cached__': 'myapp\\__pycache__\\__main__.cpython-37.pyc', '__builtins__': {'__name__': 'builtins', '__doc__': "Built-in functions, exceptions, and other objects.\n\nNoteworthy: None is the `nil' object; Ellipsis represents `...' in slices.", '__package__': '', '__loader__':

'_frozen_importlib.BuiltinImporter'>, '__spec__': ModuleSpec(name='builtins', loader=), '__build_class__': , '__import__': , 'abs':

function abs>, 'all': , 'any': , 'ascii': , 'bin': , 'breakpoint': , 'callable': , 'chr': , 'compile': , 'delattr': , 'dir': , 'divmod': , 'eval': , 'exec': , 'format': , 'getattr': , 'globals': , 'hasattr': , 'hash': , 'hex': , 'id': , 'input': , 'isinstance': , 'issubclass': , 'iter':

, 'len': , 'locals': , 'max': , 'min': , 'next': , 'oct': , 'ord': , 'pow': , 'print': , 'repr': , 'round': , 'setattr': , 'sorted': , 'sum':

sum>, 'vars': , 'None': None, 'Ellipsis': Ellipsis, 'NotImplemented': NotImplemented, 'False': False, 'True': True, 'bool': , 'memoryview': , 'bytearray': , 'bytes':

'bytes'>, 'classmethod': , 'complex': , 'dict': , 'enumerate': , 'filter': , 'float': , 'frozenset': , 'property': , 'int': , 'list': , 'map': , 'object': , 'range': , 'reversed': , 'set': , 'slice': , 'staticmethod': , 'str': , 'super': , 'tuple': , 'type': , 'zip': , '__debug__': True, 'BaseException': , 'Exception': , 'TypeError': , 'StopAsyncIteration': , 'StopIteration': , 'GeneratorExit': , 'SystemExit': , 'KeyboardInterrupt': , 'ImportError': , 'ModuleNotFoundError': , 'OSError': , 'EnvironmentError': , 'IOError': , 'WindowsError': , 'EOFError': , 'RuntimeError':

'RuntimeError'>, 'RecursionError': , 'NotImplementedError': , 'NameError': , 'UnboundLocalError': , 'AttributeError': , 'SyntaxError': , 'IndentationError': , 'TabError': , 'LookupError': , 'IndexError': , 'KeyError': , 'ValueError': , 'UnicodeError': , 'UnicodeEncodeError': , 'UnicodeDecodeError': , 'UnicodeTranslateError': , 'AssertionError': , 'ArithmeticError': , 'FloatingPointError': , 'OverflowError': , 'ZeroDivisionError': , 'SystemError': , 'ReferenceError': , 'MemoryError': , 'BufferError': , 'Warning': , 'UserWarning': , 'DeprecationWarning': , 'PendingDeprecationWarning': , 'SyntaxWarning': , 'RuntimeWarning': , 'FutureWarning': , 'ImportWarning': , 'UnicodeWarning': , 'BytesWarning': , 'ResourceWarning': , 'ConnectionError': , 'BlockingIOError': , 'BrokenPipeError': , 'ChildProcessError': , 'ConnectionAbortedError': , 'ConnectionRefusedError': , 'ConnectionResetError': , 'FileExistsError': , 'FileNotFoundError': , 'IsADirectoryError': , 'NotADirectoryError': , 'InterruptedError': , 'PermissionError': , 'ProcessLookupError': , 'TimeoutError': , 'open': , 'quit': Use quit() or Ctrl-Z plus Return to exit, 'exit': Use exit() or Ctrl-Z plus Return to exit, 'copyright': Copyright (c) 2001-2019 Python Software Foundation.

ast

literal_eval, parse, dump

>>> import ast

>>> ast.literal_eval("__import__('os')") # safer than built in function eval

Traceback (most recent call last):

File "", line 1, in

File "C:\Users\Lenovo\AppData\Local\Programs\Python\Python37-32\lib\ast.py", l

ine 91, in literal_eval

return _convert(node_or_string)

File "C:\Users\Lenovo\AppData\Local\Programs\Python\Python37-32\lib\ast.py", l

ine 90, in _convert

return _convert_signed_num(node)

File "C:\Users\Lenovo\AppData\Local\Programs\Python\Python37-32\lib\ast.py", l

ine 63, in _convert_signed_num

return _convert_num(node)

File "C:\Users\Lenovo\AppData\Local\Programs\Python\Python37-32\lib\ast.py", l

ine 55, in _convert_num

raise ValueError('malformed node or string: ' + repr(node))

ValueError: malformed node or string: <_ast.call object at>

>>> ast.literal_eval("[1, 2, 3]")

[1, 2, 3]

>>> hello_world = ast.parse("print('Hello World!')", "

>>> ast.dump(hello_world)

"Module(body=[Expr(value=Call(func=Name(id='print', ctx=Load()), args=[Str(s='He

llo World!')], keywords=[]))])"

keyword

kwlist, iskeyword

>>> import keyword

>>> keyword.kwlist

['False', 'None', 'True', 'and', 'as', 'assert', 'async', 'await', 'break', 'class', 'continue', 'def', 'de

l', 'elif', 'else', 'except', 'finally', 'for', 'from', 'global', 'if', 'import', 'in', 'is', 'lambda', 'no

nlocal', 'not', 'or', 'pass', 'raise', 'return', 'try', 'while', 'with', 'yield']

>>> keyword.iskeyword("True")

True

dis

dis, show_code, code_info

>>> import dis

>>> def func():

... print("Hello World")

...

>>> dis.dis(func)

2 0 LOAD_GLOBAL 0 (print)

2 LOAD_CONST 1 ('Hello World')

4 CALL_FUNCTION 1

6 POP_TOP

8 LOAD_CONST 0 (None)

10 RETURN_VALUE

>>> dis.show_code(func)

Name: func

Filename:

Argument count: 0

Kw-only arguments: 0

Number of locals: 0

Stack size: 2

Flags: OPTIMIZED, NEWLOCALS, NOFREE

Constants:

0: None

1: 'Hello World'

Names:

0: print

>>> dis.code_info(func)

"Name: func\nFilename: \nArgument count: 0\nKw-only arguments: 0\nNumber of locals: 0\nStack size: 2\nFlags: OPTIMIZED, NEWLOCALS, NOFREE\nConstants:\n0: None\n1: 'Hello World'\nNames:\n0: print"

tabnanny

verbose, check

>>> import tabnanny

>>> tabnanny.verbose = True

>>> tabnanny.check("tabnanny_example.py")

'tabnanny_example.py': Clean bill of health.

this

>>> import this

The Zen of Python, by Tim Peters

Beautiful is better than ugly.

Explicit is better than implicit.

Simple is better than complex.

Complex is better than complicated.

Flat is better than nested.

Sparse is better than dense.

Readability counts.

Special cases aren't special enough to break the rules.

Although practicality beats purity.

Errors should never pass silently.

Unless explicitly silenced.

In the face of ambiguity, refuse the temptation to guess.

There should be one-- and preferably only one --obvious way to do it.

Although that way may not be obvious at first unless you're Dutch.

Now is better than never.

Although never is often better than *right* now.

If the implementation is hard to explain, it's a bad idea.

If the implementation is easy to explain, it may be a good idea.

Namespaces are one honking great idea -- let's do more of those!

antigravity

>>> import antigravity

python cheatsheet,python-cheatsheet

相关阅读

相关文章

相关问答

相关文档