Python Standard Libraries Cheatsheet
Depend on Python v3.7.4
Download pdf or fork me on GitHub.
Notes:
- Every code snippet here can run independently (some needs the files that ropo provides)
- If you want to copy the code, use command to code
- You can use GETREADME.py to download README.md from the repository (Chinese or English, with or not with command line prefix can all be decided by you)
Contents
Text Processing: string
, re
, difflib
,
textwrap
, unicodedata
, readline
Data Type: datetime
, calendar
, collections
,copy
, pprint
, enum
, bisect
, heapq
Mathematical Modules: math
, cmath
, random
,
fractions
, decimal
, statistics
Functional Programming: itertools
, functools
, operator
Directory Access: pathlib
, os.path
, glob
, tempfile
,
filecmp
, fileinput
, shutil
, linecache
Data Persistence: pickle
, copyreg
Data Compression: zlib
, lzma
, zipfile
File Formats: configparser
Cryptographic Services: hashlib
, hmac
, secrets
Operating System: os
, time
, logging
,
getpass
, platform
, argparse
,
errno
, io
Networking Communication: socket
Internet Data: json
Structured Markup: html
Internet Protocols: webbrowser
Multimedia Services: wave
, sndhdr
, imghdr
,
colorsys
Program Frameworks: turtle
Graphical Interfaces: tkinter
Development Tools: typing
, doctest
Debugging Profiling: timeit
, pdb
Software Packaging: ensurepip
, zipapp
Runtime Services: sys
, dataclasses
,
contextlib
, abc
, traceback
,
__future__
, atexit
, builtins
,
inspect
Importing Modules: zipimport
, importlib
, runpy
Language Services: ast
, keyword
, dis
, tabnanny
Bonus Scene: this
, antigravity
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) # use dict to format
'my name is nick'
>>> data = ("3",) # add , to make it a tuple
>>> strcmp = "pi is about {}"
>>> formatter.format(strcmp, *data) # use tuple to format
'pi is about 3'
Template
>>> import string
>>> strcmp = "Hello $World" # the default delimiter is $
>>> t = string.Template(strcmp)
>>> t.substitute({"World": "nick"}) # use dict
'Hello nick'
>>> t.substitute(World = "nick") # use args
'Hello nick'
>>> class MyTemplate(string.Template):
... delimiter = "^"
...
>>> strcmp = "Hello ^World"
>>> mytemplate = MyTemplate(strcmp)
>>> mytemplate.substitute(World = "nick")
'Hello nick'
re
match, search, findall
>>> import re
>>> strcmp = "www.baidu.com"
>>> re.match("www", strcmp).span() # span function to get index
(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") # use regular expression
['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: # make it a html file
... 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) # 10 for an element
['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) # content over 45 will be [...]
'Hello,World! My name is nick, l am 14 [...]'
>>> textwrap.shorten(strcmp, width = 45, placeholder = "...") # change the 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') # get the symbol of the description
'{'
>>> unicodedata.name("(") # reverse to lookup
'LEFT PARENTHESIS'
>>> unicodedata.unidata_version
'11.0.0'
readline
parse_and_bind
Notice: If you are using Windows, you need to first install pyreadline module:
pip install pyreadline
>>> import readline
>>> readline.parse_and_bind('tab: complete') # use tab to autocomplete
>>> histfile = '.pythonhistory'
codecs
encode, decode, getencoder, getdecoder
>>> import codecs
>>> codecs.encode("ä½ å¥½")
b'\xe4\xbd\xa0\xe5\xa5\xbd'
>>> codecs.decode(b"\xe4\xbd\xa0\xe5\xa5\xbd")
'ä½ å¥½'
>>> codecs.getencoder("utf-8")
<built-in function utf_8_encode>
>>> codecs.getdecoder("gbk")
<built-in method decode of MultibyteCodec object at 0x0000019E080AA078>
struct
pack, unpack
Notice: The format is on struct docs
>>> import struct
>>> struct.pack(">l", 1024) # return a bytes containing the values packed according to the format string format
b'\x00\x00\x04\x00'
>>> struct.unpack(">lH", b'\x00\x00\x04\x00\xf0\xf0')
(1024, 61680)
datetime
MINYEAR, MAXYEAR, date
More Information about strftime is on strftime docs
>>> import datetime
>>> datetime.MINYEAR
1
>>> 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()
6
>>> 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) # check if it is leap year
True
>>> calendar.firstweekday()
0
>>> print(calendar.month(2019, 7)) # get the pretty calendar
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"]) # create tuple subclasses with named fields
>>> p = point(2, 1)
>>> p.x, p.y
(2, 1)
>>> deque = collections.deque(["b", "c", "d"]) # list-like container with fast appends and pops on either end
>>> deque.appendleft("a") # much faster than original list
>>> deque.append("e")
>>> deque
deque(['a', 'b', 'c', 'd', 'e'])
>>> dd = collections.defaultdict(lambda: "None") # dict which has an default value
>>> dd ["key-1"] = "value-1"
>>> dd["key-1"]
'value-1'
>>> dd["key-2"] # if the key is not exist, it will return the default value instead of raising an error
'None'
>>> od = collections.OrderedDict([("a", 1), ("b", 2)]) # dict which always keeps the order
>>> od
OrderedDict([('a', 1), ('b', 2)])
>>> c = collections.Counter() # dict subclass for counting hashable objects
>>> 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 # change when origin changes
[1, 2, ['Hello, copy', 4]]
>>> copy2 # don't change when origin changes
[1, 2, [3, 4]]
pprint
pprint
>>> import pprint # pretty print
>>> 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
<Seasons.Spring: 1>
>>> @enum.unique # don't allow same value
... class Unique(enum.Enum):
... Nick = 13
... Ben = 12
... Jack = 13
...
Traceback (most recent call last):
File "<stdin>", line 2, in <module>
File "C:\Python38\lib\enum.py", line 860, in unique
raise ValueError('duplicate values found in %r: %s' %
ValueError: duplicate values found in <enum 'Unique'>: Jack -> Nick
>>> class Auto(enum.Enum):
... VS = enum.auto()
... VSCode = enum.auto()
... Pycharm = enum.auto()
...
>>> list(Auto) # auto is from one
[<Auto.VS: 1>, <Auto.VSCode: 2>, <Auto.Pycharm: 3>]
bisect
bisect, bisect_left, bisect_right, insort, insort_left, insort_right
>>> import bisect
>>> a = [1, 2, 4, 5]
>>> bisect.bisect_left(a, 1) # if it has the same, choose left
0
>>> bisect.bisect_right(a, 1) # if it has the same, choose right
1
>>> bisect.bisect(a, 1)
1
>>> bisect.insort(a, 1) # bisect and insert
>>> 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) # first push all numbers
... return [heapq.heappop(h) for i in range(len(h))] # it was orderly extracted
...
>>> 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) # when c is deleted, b is called
>>> del c
<weakref at 0x000001C94E12F778; dead>
math
ceil, factorial, floor, modf, log, pow, sqrt, pi, e
>>> import math
>>> math.ceil(1.4) # return the smallest integer greater than or equal to x
2
>>> math.factorial(5)
120
>>> math.floor(1.6) # return the largest integer less than or equal to x
1
>>> math.modf(1.6) # return the fractional and integer parts
(0.6000000000000001, 1.0)
>>> math.log(8)
2.0794415416798357
>>> math.pow(2,5) # pow in math produces float type number, pow in builtin function produces int type number
32.0
>>> math.sqrt(9)
3.0
>>> math.pi # equal to π
3.141592653589793
>>> math.e # constant e's value
2.718281828459045
cmath
sin, tan, cos
>>> import cmath # complex maths
>>> 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() # from 0 to 1
0.6381052887323486
>>> random.uniform(5,6) # from x to y
5.325285695528384
>>> random.randint(6, 9) # include nine
9
>>> random.randrange(5, 10) # don't include ten
9
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) # fractions can do substraction
Fraction(1, 5)
>>> fractions.Fraction(1.1) # sometimes it will be strange
Fraction(2476979795053773, 2251799813685248)
>>> fractions.Fraction(1.1).limit_denominator() # use limit denominator to get right fraction
Fraction(11, 10)
>>> import math
>>> math.floor(fractions.Fraction(5, 3)) # it can also be combined with math module
1
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])
2
>>> statistics.harmonic_mean([2, 5, 10])
3.75
>>> statistics.median([2, 3, 5, 6]) # get the median of these numbers, median can not be in it
4.0
>>> statistics.median_low([2, 3, 5, 6]) # median must be in it and get the lower median
3
>>> statistics.median_high([2, 3, 5, 6]) # get the higher median
5
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!
Hello Repeat!
Hello Repeat!
Hello Repeat!
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)
55
>>> def add(a, b):
... return a+b
...
>>> functools.reduce(add, range(1,100)) # add from 1 to 100
4950
operator
lt, eq, le, ne, gt, ge, abs, pow, concat, contains, indexOf, add
>>> import operator # substitute for builtin 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)
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)
1
>>> operator.add(1, 2)
3
pathlib
Path
>>> import pathlib
>>> p = pathlib.Path(".")
>>> list(p.glob('**/*.py'))
[WindowsPath('GETREADME.py'), WindowsPath('test.py')]
>>> p/"dir" # use / to get further path
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") # join the directory and file
'./doc\\tutorial\\basic'
glob
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: # only a temp file, when we finish operating, it will be deleted
f.write(b"Hello tempfile")
f.seek(0)
f.read()
14
0
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!")
15
>>> 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!")
15
filecmp
cmp
>>> import filecmp
>>> filecmp.cmp("cmp1.txt", "cmp2.txt")
True
fileinput
input
>>> import os
>>> cmd = os.popen("python fileinput_example.py cmp1.txt") # subprocess.Popen provides more features
>>> 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") # can delete tree has contents, os.remove can't
>>> shutil.move("copysong.wav", "myapp/copysong.wav")
'myapp/copysong.wav'
linecache
getline
>>> import linecache
>>> linecache.getline("GETREADME.py", 1) # start from one, not zero
'from sys import exit\n'
pickle
loads, dumps
>>> import pickle # pickle is a python-specific compression method
>>> data = [[1, "first"],
... [2, "second"]]
>>> dumps = pickle.dumps(data) # similar to json module
>>> 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: # extract zip file
... f.extractall()
...
>>> with zipfile.ZipFile("LICENSE.zip", "a") as zip: # create zip file
... zip.write("LICENSE") # use write method to write files into zip file
...
configparser
ConfigParser
>>> import configparser
>>> config = configparser.ConfigParser() # create an instance
>>> config.read("config.ini")
['config.ini']
>>> config.sections()
['python', 'java']
>>> config["python"]["type"] # all sections has values in DEFAULT
'programming language'
>>> config["java"]["popular"]
'1'
hashlib
md5
>>> import hashlib
>>> md5 = hashlib.md5()
>>> md5.update(b"Hello World") # use update method to join in batches
>>> md5.block_size
64
>>> md5.digest_size
16
>>> 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" # use key to encrypt
>>> 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!") # choose one character from the string
'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'
os
name, getcwd
>>> import os
>>> os.name
'nt'
>>> os.getcwd() # get the working directory now
'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
More details about format for logging is on logging docs
>>> 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") # customize the level
2019-07-29 12:31:59,758 - __main__ - Level 35 - log
getpass
getpass, getuser
>>> import getpass
>>> password = getpass.getpass() # what you enter will not be displayed on the screen
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)
3
10
>>> 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'}
io
StringIO, BytesIO
>>> import io
>>> stringio = io.StringIO() # similar as file operation
>>> stringio.write("Hello World!")
12
>>> stringio.seek(6)
6
>>> stringio.read()
'World!'
>>> stringio.close()
>>> bytesio = io.BytesIO()
>>> bytesio.write(b"Hello World")
11
>>> bytesio.seek(0)
0
>>> bytesio.read()
b'Hello World'
>>> bytesio.close()
socket
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 # it can draw a five-pointed star
>>> 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
details in tkinter docs
run in bash:
python tkinter_example.py
typing
List, NewType
>>> import typing
>>> lst = typing.List[int] # list full of 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)
70
doctest
testfile
>>> import doctest
>>> doctest.testfile("doctest_example.txt", verbose=True)
Trying:
from doctest_example import factorial
Expecting nothing
ok
Trying:
[factorial(n) for n in range(6)]
Expecting:
[1, 1, 2, 6, 24, 120]
ok
Trying:
factorial(30)
Expecting:
265252859812191058636308480000000
ok
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):\n lst.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()
> <stdin>(5)foo()
(Pdb) p i
0
(Pdb) p lst
[]
(Pdb) n
> <stdin>(3)foo()
(Pdb) list
[EOF]
(Pdb) n
> <stdin>(4)foo()
(Pdb) r
> <stdin>(5)foo()
(Pdb) p i
1
(Pdb) p lst
[0]
(Pdb) q
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "<stdin>", line 5, in foo
File "<stdin>", 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() # pyz file can also be executed
'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()
...
(<class 'ZeroDivisionError'>, ZeroDivisionError('division by zero'), <traceback object at 0x000002D8BF38A248>)
>>> 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
__enter__ cm
Hello,pynickle Hello,bob
__exit__ cm
__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
<class '__main__.UserTwo'>
>>> 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 "<stdin>", line 2, in <module>
ZeroDivisionError: division by zero
future
division, absolute_import, print_function, unicode_literals
>>> from __future__ import division, absolute_import, print_function, unicode_literals
atexit
register
>>> import atexit
>>> def bye():
... print("bye!")
...
>>> atexit.register(bye)
<function bye at 0x004B0858>
>>> exit()
bye!
builtins
range
>>> import builtins
>>> for i in builtins.range(10):
... print(i)
...
0
1
2
3
4
5
6
7
8
9
inspect
getmembers, ismethod, isfunction, isclass, isbuiltin
>>> import inspect
>>> inspect.getmembers([1, 2, 3])
[('__add__', <method-wrapper '__add__' of list object at 0x000002644D026148>), ('__class__', <class 'list'>), ('__contains__', <method-wrapper '__contains__' of list object at 0x000002644D026148>), ('__delattr__', <method-wrapper '__delattr__' of list object at 0x000002644D026148>), ('__delitem__', <method-wrapper '__delitem__' of list object at 0x000002644D026148>), ('__dir__', <built-in method __dir__ of list object at 0x000002644D026148>), ('__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__', <method-wrapper '__eq__' of list object at 0x000002644D026148>), ('__format__', <built-in method __format__ of list object at 0x000002644D026148>), ('__ge__', <method-wrapper '__ge__' of list object at 0x000002644D026148>), ('__getattribute__', <method-wrapper '__getattribute__' of list object at 0x000002644D026148>), ('__getitem__', <built-in method __getitem__ of list object at 0x000002644D026148>), ('__gt__', <method-wrapper '__gt__' of list object at 0x000002644D026148>), ('__hash__', None), ('__iadd__', <method-wrapper '__iadd__' of list object at 0x000002644D026148>), ('__imul__', <method-wrapper '__imul__' of list object at 0x000002644D026148>), ('__init__', <method-wrapper '__init__' of list object at 0x000002644D026148>), ('__init_subclass__', <built-in method __init_subclass__ of type object at 0x00007FFB5C9A2D30>), ('__iter__', <method-wrapper '__iter__' of list object at 0x000002644D026148>), ('__le__', <method-wrapper '__le__' of list object at 0x000002644D026148>), ('__len__', <method-wrapper '__len__' of list object at 0x000002644D026148>), ('__lt__', <method-wrapper '__lt__' of list object at 0x000002644D026148>), ('__mul__', <method-wrapper '__mul__' of list object at 0x000002644D026148>), ('__ne__', <method-wrapper '__ne__' of list object at 0x000002644D026148>), ('__new__', <built-in method __new__ of type object at 0x00007FFB5C9A2D30>), ('__reduce__', <built-in method __reduce__ of list object at 0x000002644D026148>), ('__reduce_ex__', <built-in method __reduce_ex__ of list object at 0x000002644D026148>), ('__repr__', <method-wrapper '__repr__' of list object at 0x000002644D026148>), ('__reversed__', <built-in method __reversed__ of list object at 0x000002644D026148>), ('__rmul__', <method-wrapper '__rmul__' of list object at 0x000002644D026148>), ('__setattr__', <method-wrapper '__setattr__' of list object at 0x000002644D026148>), ('__setitem__', <method-wrapper '__setitem__' of list object at 0x000002644D026148>), ('__sizeof__', <built-in method __sizeof__ of list object at 0x000002644D026148>), ('__str__', <method-wrapper '__str__' of list object at 0x000002644D026148>), ('__subclasshook__', <built-in method __subclasshook__ of type object at 0x00007FFB5C9A2D30>), ('append', <built-in method append of list object at 0x000002644D026148>), ('clear', <built-in method clear of list object at 0x000002644D026148>), ('copy', <built-in method copy of list object at 0x000002644D026148>), ('count', <built-in method count of list object at 0x000002644D026148>), ('extend', <built-in method extend of list object at 0x000002644D026148>), ('index', <built-in method index of list object at 0x000002644D026148>), ('insert', <built-in method insert of list object at 0x000002644D026148>), ('pop', <built-in method pop of list object at 0x000002644D026148>), ('remove', <built-in method remove of list object at 0x000002644D026148>), ('reverse', <built-in method reverse of list object at 0x000002644D026148>), ('sort', <built-in method sort of list object at 0x000002644D026148>)]
>>> 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
<module 'GETREADME' from 'GETREADME.zip\\GETREADME.py'>
>>> 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)
<module 'sys' (built-in)>
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 0x000001AF031DFE88>, '__package__': '', '__spec__': ModuleSpec(name='app', loader=<_frozen_importlib_external.SourceFileLoader object at 0x000001AF031DFE88>, 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__': <class '_frozen_importlib.BuiltinImporter'>, '__spec__': ModuleSpec(name='builtins', loader=<class '_frozen_importlib.BuiltinImporter'>), '__build_class__': <built-in function __build_class__>, '__import__': <built-in function __import__>, 'abs': <built-in function abs>, 'all': <built-in function all>, 'any': <built-in function any>, 'ascii': <built-in function ascii>, 'bin': <built-in function bin>, 'breakpoint': <built-in function breakpoint>, 'callable': <built-in function callable>, 'chr': <built-in function chr>, 'compile': <built-in function compile>, 'delattr': <built-in function delattr>, 'dir': <built-in function dir>, 'divmod': <built-in function divmod>, 'eval': <built-in function eval>, 'exec': <built-in function exec>, 'format': <built-in
function format>, 'getattr': <built-in function getattr>, 'globals': <built-in function globals>, 'hasattr': <built-in function hasattr>, 'hash': <built-in function hash>, 'hex': <built-in function hex>, 'id': <built-in function id>, 'input': <built-in function input>, 'isinstance': <built-in function isinstance>, 'issubclass': <built-in function issubclass>, 'iter': <built-in function iter>, 'len': <built-in function len>, 'locals': <built-in function locals>, 'max': <built-in function max>, 'min': <built-in function min>, 'next': <built-in function next>, 'oct': <built-in function oct>, 'ord': <built-in function ord>, 'pow': <built-in function pow>, 'print': <built-in function print>, 'repr': <built-in function repr>, 'round': <built-in function round>, 'setattr': <built-in function setattr>, 'sorted': <built-in function sorted>, 'sum': <built-in function sum>, 'vars': <built-in function vars>, 'None': None, 'Ellipsis': Ellipsis, 'NotImplemented': NotImplemented, 'False': False, 'True': True, 'bool': <class 'bool'>, 'memoryview': <class 'memoryview'>, 'bytearray': <class 'bytearray'>, 'bytes': <class 'bytes'>, 'classmethod': <class 'classmethod'>, 'complex': <class 'complex'>, 'dict': <class 'dict'>, 'enumerate': <class 'enumerate'>, 'filter': <class 'filter'>, 'float': <class 'float'>, 'frozenset': <class 'frozenset'>, 'property': <class 'property'>, 'int': <class 'int'>, 'list': <class 'list'>, 'map': <class 'map'>, 'object': <class 'object'>, 'range': <class 'range'>, 'reversed': <class 'reversed'>, 'set': <class 'set'>, 'slice': <class 'slice'>, 'staticmethod': <class 'staticmethod'>, 'str':
<class 'str'>, 'super': <class 'super'>, 'tuple': <class 'tuple'>, 'type': <class 'type'>, 'zip': <class 'zip'>, '__debug__': True, 'BaseException': <class 'BaseException'>, 'Exception': <class 'Exception'>, 'TypeError': <class 'TypeError'>, 'StopAsyncIteration': <class 'StopAsyncIteration'>, 'StopIteration': <class 'StopIteration'>, 'GeneratorExit': <class 'GeneratorExit'>, 'SystemExit': <class 'SystemExit'>, 'KeyboardInterrupt': <class 'KeyboardInterrupt'>, 'ImportError': <class 'ImportError'>, 'ModuleNotFoundError': <class 'ModuleNotFoundError'>, 'OSError': <class 'OSError'>, 'EnvironmentError': <class 'OSError'>,
'IOError': <class 'OSError'>, 'WindowsError': <class 'OSError'>, 'EOFError': <class 'EOFError'>, 'RuntimeError': <class 'RuntimeError'>, 'RecursionError': <class 'RecursionError'>, 'NotImplementedError': <class 'NotImplementedError'>, 'NameError': <class 'NameError'>, 'UnboundLocalError': <class 'UnboundLocalError'>, 'AttributeError': <class 'AttributeError'>, 'SyntaxError': <class 'SyntaxError'>, 'IndentationError': <class 'IndentationError'>, 'TabError': <class 'TabError'>, 'LookupError': <class 'LookupError'>, 'IndexError': <class 'IndexError'>, 'KeyError': <class 'KeyError'>, 'ValueError': <class 'ValueError'>, 'UnicodeError': <class 'UnicodeError'>, 'UnicodeEncodeError': <class 'UnicodeEncodeError'>, 'UnicodeDecodeError': <class 'UnicodeDecodeError'>, 'UnicodeTranslateError': <class 'UnicodeTranslateError'>, 'AssertionError': <class 'AssertionError'>, 'ArithmeticError': <class 'ArithmeticError'>, 'FloatingPointError': <class 'FloatingPointError'>, 'OverflowError': <class 'OverflowError'>, 'ZeroDivisionError': <class 'ZeroDivisionError'>, 'SystemError': <class 'SystemError'>, 'ReferenceError': <class 'ReferenceError'>, 'MemoryError': <class 'MemoryError'>, 'BufferError': <class 'BufferError'>, 'Warning': <class 'Warning'>, 'UserWarning': <class 'UserWarning'>, 'DeprecationWarning': <class 'DeprecationWarning'>, 'PendingDeprecationWarning': <class 'PendingDeprecationWarning'>, 'SyntaxWarning': <class 'SyntaxWarning'>, 'RuntimeWarning': <class 'RuntimeWarning'>, 'FutureWarning': <class 'FutureWarning'>, 'ImportWarning': <class 'ImportWarning'>, 'UnicodeWarning': <class 'UnicodeWarning'>, 'BytesWarning': <class 'BytesWarning'>, 'ResourceWarning': <class 'ResourceWarning'>, 'ConnectionError': <class 'ConnectionError'>, 'BlockingIOError': <class 'BlockingIOError'>, 'BrokenPipeError': <class 'BrokenPipeError'>, 'ChildProcessError': <class 'ChildProcessError'>, 'ConnectionAbortedError': <class 'ConnectionAbortedError'>, 'ConnectionRefusedError': <class 'ConnectionRefusedError'>, 'ConnectionResetError': <class 'ConnectionResetError'>, 'FileExistsError': <class 'FileExistsError'>, 'FileNotFoundError': <class 'FileNotFoundError'>, 'IsADirectoryError': <class 'IsADirectoryError'>, 'NotADirectoryError': <class 'NotADirectoryError'>, 'InterruptedError': <class 'InterruptedError'>, 'PermissionError': <class 'PermissionError'>, 'ProcessLookupError': <class 'ProcessLookupError'>, 'TimeoutError': <class 'TimeoutError'>, 'open': <built-in function 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.
All Rights Reserved.
Copyright (c) 2000 BeOpen.com.
All Rights Reserved.
Copyright (c) 1995-2001 Corporation for National Research Initiatives.
All Rights Reserved.
Copyright (c) 1991-1995 Stichting Mathematisch Centrum, Amsterdam.
All Rights Reserved., 'credits': Thanks to CWI, CNRI, BeOpen.com, Zope Corporation and a cast of thousands
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__': '<run_path>', '__doc__': None, '__package__': '', '__loader__': <_frozen_importlib_external.SourceFileLoader object at 0x000001AF031A5B88>, '__spec__': ModuleSpec(name='__main__', loader=<_frozen_importlib_external.SourceFileLoader object at 0x000001AF031A5B88>, 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__': <class
'_frozen_importlib.BuiltinImporter'>, '__spec__': ModuleSpec(name='builtins', loader=<class '_frozen_importlib.BuiltinImporter'>), '__build_class__': <built-in function __build_class__>, '__import__': <built-in function __import__>, 'abs': <built-in
function abs>, 'all': <built-in function all>, 'any': <built-in function any>, 'ascii': <built-in function ascii>, 'bin': <built-in function bin>, 'breakpoint': <built-in function breakpoint>, 'callable': <built-in function callable>, 'chr': <built-in function chr>, 'compile': <built-in function compile>, 'delattr': <built-in function delattr>, 'dir': <built-in function dir>, 'divmod': <built-in function divmod>, 'eval': <built-in function eval>, 'exec': <built-in function exec>, 'format': <built-in function format>, 'getattr': <built-in function getattr>, 'globals': <built-in function globals>, 'hasattr': <built-in function hasattr>, 'hash': <built-in function hash>, 'hex': <built-in function hex>, 'id': <built-in function id>, 'input': <built-in function input>, 'isinstance': <built-in function isinstance>, 'issubclass': <built-in function issubclass>, 'iter':
<built-in function iter>, 'len': <built-in function len>, 'locals': <built-in function locals>, 'max': <built-in function max>, 'min': <built-in function min>, 'next': <built-in function next>, 'oct': <built-in function oct>, 'ord': <built-in function ord>, 'pow': <built-in function pow>, 'print': <built-in function print>, 'repr': <built-in function repr>, 'round': <built-in function round>, 'setattr': <built-in function setattr>, 'sorted': <built-in function sorted>, 'sum': <built-in function
sum>, 'vars': <built-in function vars>, 'None': None, 'Ellipsis': Ellipsis, 'NotImplemented': NotImplemented, 'False': False, 'True': True, 'bool': <class 'bool'>, 'memoryview': <class 'memoryview'>, 'bytearray': <class 'bytearray'>, 'bytes': <class
'bytes'>, 'classmethod': <class 'classmethod'>, 'complex': <class 'complex'>, 'dict': <class 'dict'>, 'enumerate': <class 'enumerate'>, 'filter': <class 'filter'>, 'float': <class 'float'>, 'frozenset': <class 'frozenset'>, 'property': <class 'property'>, 'int': <class 'int'>, 'list': <class 'list'>, 'map': <class 'map'>, 'object': <class 'object'>, 'range': <class 'range'>, 'reversed': <class 'reversed'>, 'set': <class 'set'>, 'slice': <class 'slice'>, 'staticmethod': <class 'staticmethod'>, 'str': <class 'str'>, 'super': <class 'super'>, 'tuple': <class 'tuple'>, 'type': <class 'type'>, 'zip': <class 'zip'>, '__debug__': True, 'BaseException': <class 'BaseException'>, 'Exception': <class 'Exception'>, 'TypeError': <class 'TypeError'>, 'StopAsyncIteration': <class 'StopAsyncIteration'>, 'StopIteration': <class 'StopIteration'>, 'GeneratorExit': <class 'GeneratorExit'>, 'SystemExit': <class 'SystemExit'>, 'KeyboardInterrupt': <class 'KeyboardInterrupt'>, 'ImportError': <class 'ImportError'>, 'ModuleNotFoundError': <class 'ModuleNotFoundError'>, 'OSError': <class 'OSError'>, 'EnvironmentError': <class 'OSError'>, 'IOError': <class 'OSError'>, 'WindowsError': <class 'OSError'>, 'EOFError': <class 'EOFError'>, 'RuntimeError': <class
'RuntimeError'>, 'RecursionError': <class 'RecursionError'>, 'NotImplementedError': <class 'NotImplementedError'>, 'NameError': <class 'NameError'>, 'UnboundLocalError': <class 'UnboundLocalError'>, 'AttributeError': <class 'AttributeError'>, 'SyntaxError': <class 'SyntaxError'>, 'IndentationError': <class 'IndentationError'>, 'TabError': <class 'TabError'>, 'LookupError': <class 'LookupError'>, 'IndexError': <class 'IndexError'>, 'KeyError': <class 'KeyError'>, 'ValueError': <class 'ValueError'>, 'UnicodeError': <class 'UnicodeError'>, 'UnicodeEncodeError': <class 'UnicodeEncodeError'>, 'UnicodeDecodeError': <class 'UnicodeDecodeError'>, 'UnicodeTranslateError': <class 'UnicodeTranslateError'>, 'AssertionError': <class 'AssertionError'>, 'ArithmeticError': <class 'ArithmeticError'>, 'FloatingPointError': <class 'FloatingPointError'>, 'OverflowError': <class 'OverflowError'>, 'ZeroDivisionError': <class 'ZeroDivisionError'>, 'SystemError': <class 'SystemError'>, 'ReferenceError': <class 'ReferenceError'>, 'MemoryError': <class 'MemoryError'>, 'BufferError': <class 'BufferError'>, 'Warning': <class 'Warning'>, 'UserWarning': <class 'UserWarning'>, 'DeprecationWarning': <class 'DeprecationWarning'>, 'PendingDeprecationWarning': <class 'PendingDeprecationWarning'>, 'SyntaxWarning': <class 'SyntaxWarning'>, 'RuntimeWarning': <class 'RuntimeWarning'>, 'FutureWarning': <class 'FutureWarning'>, 'ImportWarning': <class 'ImportWarning'>, 'UnicodeWarning': <class 'UnicodeWarning'>, 'BytesWarning': <class 'BytesWarning'>, 'ResourceWarning': <class 'ResourceWarning'>, 'ConnectionError': <class 'ConnectionError'>, 'BlockingIOError': <class 'BlockingIOError'>, 'BrokenPipeError': <class 'BrokenPipeError'>, 'ChildProcessError': <class 'ChildProcessError'>, 'ConnectionAbortedError': <class 'ConnectionAbortedError'>, 'ConnectionRefusedError': <class 'ConnectionRefusedError'>, 'ConnectionResetError': <class 'ConnectionResetError'>, 'FileExistsError': <class 'FileExistsError'>, 'FileNotFoundError': <class 'FileNotFoundError'>, 'IsADirectoryError': <class 'IsADirectoryError'>, 'NotADirectoryError': <class 'NotADirectoryError'>, 'InterruptedError': <class 'InterruptedError'>, 'PermissionError': <class 'PermissionError'>, 'ProcessLookupError': <class 'ProcessLookupError'>, 'TimeoutError': <class 'TimeoutError'>, 'open': <built-in function 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.
All Rights Reserved.
Copyright (c) 2000 BeOpen.com.
All Rights Reserved.
Copyright (c) 1995-2001 Corporation for National Research Initiatives.
All Rights Reserved.
Copyright (c) 1991-1995 Stichting Mathematisch Centrum, Amsterdam.
All Rights Reserved., 'credits': Thanks to CWI, CNRI, BeOpen.com, Zope Corporation and a cast of thousands
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}}
ast
literal_eval, parse, dump
>>> import ast
>>> ast.literal_eval("__import__('os')") # safer than built in function eval
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
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 0x00B11C50>
>>> ast.literal_eval("[1, 2, 3]")
[1, 2, 3]
>>> hello_world = ast.parse("print('Hello World!')", "<string)", "exec") # abstract syntax trees
>>> 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: <stdin>
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: <stdin>\nArgument count: 0\nKw-only arguments: 0\nNumber of locals: 0\nStack size: 2\nFlags: OPTIMIZED, NEWLOCALS, NOFREE\nConstants:\n 0: None\n 1: 'Hello World'\nNames:\n 0: print"
tabnanny
verbose, check
>>> import tabnanny
>>> tabnanny.verbose = True
>>> tabnanny.check("tabnanny_example.py")
'tabnanny_example.py': *** Line 3: trouble in tab city! ***
offending line: '\tprint(i)'
indent not greater e.g. at tab sizes 1, 2, 3, 4
this
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
antigravity
>>> import antigravity