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1. Collections: List, Dictionary, Set, Tuple, Range, Enumerate, Iterator, Generator.
2. Types: Type, String, Regular_Exp, Format, Numbers, Combinatorics, Datetime.
3. Syntax: Args, Inline, Import, Decorator, Class, Duck_Types, Enum, Exception.
4. System: Exit, Print, Input, Command_Line_Arguments, Open, Path, OS_Commands.
5. Data: JSON, Pickle, CSV, SQLite, Bytes, Struct, Array, Memory_View, Deque.
6. Advanced: Threading, Operator, Introspection, Metaprograming, Eval, Coroutines.
7. Libraries: Progress_Bar, Plot, Tables, Curses, Logging, Scraping, Web, Profile.
8. Multimedia: NumPy, Image, Animation, Audio, Pygame, Pandas, Plotly, PySimpleGUI.
if __name__ == '__main__': # Runs main() if file wasn't imported.
main()<list> = <list>[<slice>] # Or: <list>[from_inclusive : to_exclusive : ±step]<list>.append(<el>) # Or: <list> += [<el>]
<list>.extend(<collection>) # Or: <list> += <collection><list>.sort() # Sorts in ascending order.
<list>.reverse() # Reverses the list in-place.
<list> = sorted(<collection>) # Returns a new sorted list.
<iter> = reversed(<list>) # Returns reversed iterator.sum_of_elements = sum(<collection>)
elementwise_sum = [sum(pair) for pair in zip(list_a, list_b)]
sorted_by_second = sorted(<collection>, key=lambda el: el[1])
sorted_by_both = sorted(<collection>, key=lambda el: (el[1], el[0]))
flatter_list = list(itertools.chain.from_iterable(<list>))
product_of_elems = functools.reduce(lambda out, el: out * el, <collection>)
list_of_chars = list(<str>)- For details about sorted(), min() and max() see sortable.
- Module operator provides functions itemgetter() and mul() that offer the same functionality as lambda expressions above.
<list>.insert(<int>, <el>) # Inserts item at index and moves the rest to the right.
<el> = <list>.pop([<int>]) # Removes and returns item at index or from the end.
<int> = <list>.count(<el>) # Returns number of occurrences. Also works on strings.
<int> = <list>.index(<el>) # Returns index of the first occurrence or raises ValueError.
<list>.remove(<el>) # Removes first occurrence of the item or raises ValueError.
<list>.clear() # Removes all items. Also works on dictionary and set.<view> = <dict>.keys() # Coll. of keys that reflects changes.
<view> = <dict>.values() # Coll. of values that reflects changes.
<view> = <dict>.items() # Coll. of key-value tuples that reflects chgs.value = <dict>.get(key, default=None) # Returns default if key is missing.
value = <dict>.setdefault(key, default=None) # Returns and writes default if key is missing.
<dict> = collections.defaultdict(<type>) # Returns a dict with default value `<type>()`.
<dict> = collections.defaultdict(lambda: 1) # Returns a dict with default value 1.<dict> = dict(<collection>) # Creates a dict from coll. of key-value pairs.
<dict> = dict(zip(keys, values)) # Creates a dict from two collections.
<dict> = dict.fromkeys(keys [, value]) # Creates a dict from collection of keys.<dict>.update(&l
D2F7
t;dict>) # Adds items. Replaces ones with matching keys.
value = <dict>.pop(key) # Removes item or raises KeyError if missing.
{k for k, v in <dict>.items() if v == value} # Returns set of keys that point to the value.
{k: v for k, v in <dict>.items() if k in keys} # Returns a dictionary, filtered by keys.>>> from collections import Counter
>>> colors = ['blue', 'blue', 'blue', 'red', 'red']
>>> counter = Counter(colors)
>>> counter['yellow'] += 1
Counter({'blue': 3, 'red': 2, 'yellow': 1})
>>> counter.most_common()[0]
('blue', 3)<set> = set() # `{}` returns a dictionary.<set>.add(<el>) # Or: <set> |= {<el>}
<set>.update(<collection> [, ...]) # Or: <set> |= <set><set> = <set>.union(<coll.>) # Or: <set> | <set>
<set> = <set>.intersection(<coll.>) # Or: <set> & <set>
<set> = <set>.difference(<coll.>) # Or: <set> - <set>
<set> = <set>.symmetric_difference(<coll.>) # Or: <set> ^ <set>
<bool> = <set>.issubset(<coll.>) # Or: <set> <= <set>
<bool> = <set>.issuperset(<coll.>) # Or: <set> >= <set><el> = <set>.pop() # Raises KeyError if empty.
<set>.remove(<el>) # Raises KeyError if missing.
<set>.discard(<el>) # Doesn't raise an error.- Is immutable and hashable.
- That means it can be used as a key in a dictionary or as an element in a set.
<frozenset> = frozenset(<collection>)Tuple is an immutable and hashable list.
<tuple> = () # Empty tuple.
<tuple> = (<el>,) # Or: <el>,
<tuple> = (<el_1>, <el_2> [, ...]) # Or: <el_1>, <el_2> [, ...]Tuple's subclass with named elements.
>>> from collections import namedtuple
>>> Point = namedtuple('Point', 'x y')
>>> p = Point(1, y=2)
Point(x=1, y=2)
>>> p[0]
1
>>> p.x
1
>>> getattr(p, 'y')
2Immutable and hashable sequence of integers.
<range> = range(stop) # range(to_exclusive)
<range> = range(start, stop) # range(from_inclusive, to_exclusive)
<range> = range(start, stop, ±step) # range(from_inclusive, to_exclusive, ±step_size)>>> [i for i in range(3)]
[0, 1, 2]for i, el in enumerate(<collection> [, i_start]):
...<iter> = iter(<collection>) # `iter(<iter>)` returns unmodified iterator.
<iter> = iter(<function>, to_exclusive) # A sequence of return values until 'to_exclusive'.
<el> = next(<iter> [, default]) # Raises StopIteration or returns 'default' on end.
<list> = list(<iter>) # Returns a list of iterator's remaining elements.import itertools as it<iter> = it.count(start=0, step=1) # Returns updated value endlessly. Accepts floats.
<iter> = it.repeat(<el> [, times]) # Returns element endlessly or 'times' times.
<iter> = it.cycle(<collection>) # Repeats the sequence endlessly.<iter> = it.chain(<coll>, <coll> [, ...]) # Empties collections in order (figuratively).
<iter> = it.chain.from_iterable(<coll>) # Empties collections inside a collection in order.<iter> = it.islice(<coll>, to_exclusive) # Only returns first 'to_exclusive' elements.
<iter> = it.islice(<coll>, from_inc, …) # `to_exclusive, +step_size`. Indices can be None.- Any function that contains a yield statement returns a generator.
- Generators and iterators are interchangeable.
def count(start, step):
while True:
yield start
start += step>>> counter = count(10, 2)
>>> next(counter), next(counter), next(counter)
(10, 12, 14)- Everything is an object.
- Every object has a type.
- Type and class are synonymous.
<type> = type(<el>) # Or: <el>.__class__
<bool> = isinstance(<el>, <type>) # Or: issubclass(type(<el>), <type>)>>> type('a'), 'a'.__class__, str
(<class 'str'>, <class 'str'>, <class 'str'>)from types import FunctionType, MethodType, LambdaType, GeneratorType, ModuleTypeEach abstract base class specifies a set of virtual subclasses. These classes are then recognized by isinstance() and issubclass() as subclasses of the ABC, although they are really not. ABC can also manually decide whether or not a specific class is its virtual subclass, usually based on which methods the class has implemented. For instance, Iterable ABC looks for method iter(), while Collection ABC looks for iter(), contains() and len().
>>> from collections.abc import Iterable, Collection, Sequence
>>> isinstance([1, 2, 3], Iterable)
True+------------------+------------+------------+------------+
| | Iterable | Collection | Sequence |
+------------------+------------+------------+------------+
| list, range, str | yes | yes | yes |
| dict, set | yes | yes | |
| iter | yes | | |
+------------------+------------+------------+------------+
>>> from numbers import Number, Complex, Real, Rational, Integral
>>> isinstance(123, Number)
True+--------------------+----------+----------+----------+----------+----------+
| | Number | Complex | Real | Rational | Integral |
+--------------------+----------+----------+----------+----------+----------+
| int | yes | yes | yes | yes | yes |
| fractions.Fraction | yes | yes | yes | yes | |
| float | yes | yes | yes | | |
| complex | yes | yes | | | |
| decimal.Decimal | yes | | | | |
+--------------------+----------+----------+----------+----------+----------+
<str> = <str>.strip() # Strips all whitespace characters from both ends.
<str> = <str>.strip('<chars>') # Strips all passed characters from both ends.<list> = <str>.split() # Splits on one or more whitespace characters.
<list> = <str>.split(sep=None, maxsplit=-1) # Splits on 'sep' str at most 'maxsplit' times.
<list> = <str>.splitlines(keepends=False) # On [\n\r\f\v\x1c-\x1e\x85\u2028\u2029] and \r\n.
<str> = <str>.join(<coll_of_strings>) # Joins elements using string as a separator.<bool> = <sub_str> in <str> # Checks if string contains the substring.
<bool> = <str>.startswith(<sub_str>) # Pass tuple of strings for multiple options.
<bool> = <str>.endswith(<sub_str>) # Pass tuple of strings for multiple options.
<int> = <str>.find(<sub_str>) # Returns start index of the first match or -1.
<int> = <str>.index(<sub_str>) # Same, but raises ValueError if missing.<str> = <str>.replace(old, new [, count]) # Replaces 'old' with 'new' at most 'count' times.
<str> = <str>.translate(<table>) # Use `str.maketrans(<dict>)` to generate table.<str> = chr(<int>) # Converts int to Unicode character.
<int> = ord(<str>) # Converts Unicode character to int.- Also:
'lstrip()','rstrip()'and'rsplit()'. - Also:
'lower()','upper()','capitalize()'and'title()'.
+---------------+----------+----------+----------+----------+----------+
| | [ !#$%…] | [a-zA-Z] | [¼½¾] | [²³¹] | [0-9] |
+---------------+----------+----------+----------+----------+----------+
| isprintable() | yes | yes | yes | yes | yes |
| isalnum() | | yes | yes | yes | yes |
| isnumeric() | | | yes | yes | yes |
| isdigit() | | | | yes | yes |
| isdecimal() | | | | | yes |
+---------------+----------+----------+----------+----------+----------+
'isspace()'checks for whitespaces:'[ \t\n\r\f\v\x1c-\x1f\x85\xa0\u1680…]'.
import re
<str> = re.sub(<regex>, new, text, count=0) # Substitutes all occurrences with 'new'.
<list> = re.findall(<regex>, text) # Returns all occurrences as strings.
<list> = re.split(<regex>, text, maxsplit=0) # Add brackets around regex to include matches.
<Match> = re.search(<regex>, text) # Searches for first occurrence of the pattern.
<Match> = re.match(<regex>, text) # Searches only at the beginning of the text.
<iter> = re.finditer(<regex>, text) # Returns all occurrences as Match objects.- Argument 'new' can be a function that accepts a Match object and returns a string.
- Search() and match() return None if they can't find a match.
- Argument
'flags=re.IGNORECASE'can be used with all functions. - Argument
'flags=re.MULTILINE'makes'^'and'$'match the start/end of each line. - Argument
'flags=re.DOTALL'makes'.'also accept the'\n'. - Use
r'\1'or'\\1'for backreference ('\1'returns a character with octal code 1). - Add
'?'after'*'and'+'to make them non-greedy.
<str> = <Match>.group() # Returns the whole match. Also group(0).
<str> = <Match>.group(1) # Returns the part inside first brackets.
<tuple> = <Match>.groups() # Returns all bracketed parts.
<int> = <Match>.start() # Returns start index of the match.
<int> = <Match>.end() # Returns exclusive end index of the match.'\d' == '[0-9]' # Matches decimal characters.
'\w' == '[a-zA-Z0-9_]' # Matches alphanumerics and underscore.
'\s' == '[ \t\n\r\f\v]' # Matches whitespaces.- By default, decimal characters, alphanumerics and whitespaces from all alphabets are matched unless
'flags=re.ASCII'argument is used. - As shown above, it restricts all special sequence matches to the first 128 characters and prevents
'\s'from accepting'[\x1c-\x1f]'(the so-called separator characters). - Use a capital letter for negation (all non-ASCII characters will be matched when used in combination with ASCII flag).
<str> = f'{<el_1>}, {<el_2>}' # Curly brackets can also contain expressions.
<str> = '{}, {}'.format(<el_1>, <el_2>) # Or: '{0}, {a}'.format(<el_1>, a=<el_2>)
<str> = '%s, %s' % (<el_1>, <el_2>) # Redundant and inferior C-style formatting.>>> Person = collections.namedtuple('Person', 'name height')
>>> person = Person('Jean-Luc', 187)
>>> f'{person.name} is {person.height / 100} meters tall.'
'Jean-Luc is 1.87 meters tall.'{<el>:<10} # '<el> '
{<el>:^10} # ' <el> '
{<el>:>10} # ' <el>'
{<el>:.<10} # '<el>......'
{<el>:0} # '<el>'- Options can be generated dynamically:
f'{<el>:{<str/int>}[…]}'. - Adding
'='to the expression prepends it to the output:f'{1+1=}'returns'1+1=2'. - Adding
'!r'to the expression converts object to string by calling its repr() method.
{'abcde':10} # 'abcde '
{'abcde':10.3} # 'abc '
{'abcde':.3} # 'abc'
{'abcde'!r:10} # "'abcde' "{123456:10} # ' 123456'
{123456:10,} # ' 123,456'
{123456:10_} # ' 123_456'
{123456:+10} # ' +123456'
{123456:=+10} # '+ 123456'
{123456: } # ' 123456'
{-123456: } # '-123456'{1.23456:10.3} # ' 1.23'
{1.23456:10.3f} # ' 1.235'
{1.23456:10.3e} # ' 1.235e+00'
{1.23456:10.3%} # ' 123.456%'+--------------+----------------+----------------+----------------+----------------+
| | {<float>} | {<float>:f} | {<float>:e} | {<float>:%} |
+--------------+----------------+----------------+----------------+----------------+
| 0.000056789 | '5.6789e-05' | '0.000057' | '5.678900e-05' | '0.005679%' |
| 0.00056789 | '0.00056789' | '0.000568' | '5.678900e-04' | '0.056789%' |
| 0.0056789 | '0.0056789' | '0.005679' | '5.678900e-03' | '0.567890%' |
| 0.056789 | '0.056789' | '0.056789' | '5.678900e-02' | '5.678900%' |
| 0.56789 | '0.56789' | '0.567890' | '5.678900e-01' | '56.789000%' |
| 5.6789 | '5.6789' | '5.678900' | '5.678900e+00' | '567.890000%' |
| 56.789 | '56.789' | '56.789000' | '5.678900e+01' | '5678.900000%' |
+--------------+----------------+----------------+----------------+----------------+
+--------------+----------------+----------------+----------------+----------------+
| | {<float>:.2} | {<float>:.2f} | {<float>:.2e} | {<float>:.2%} |
+--------------+----------------+----------------+----------------+----------------+
| 0.000056789 | '5.7e-05' | '0.00' | '5.68e-05' | '0.01%' |
| 0.00056789 | '0.00057' | '0.00' | '5.68e-04' | '0.06%' |
| 0.0056789 | '0.0057' | '0.01' | '5.68e-03' | '0.57%' |
| 0.056789 | '0.057' | '0.06' | '5.68e-02' | '5.68%' |
| 0.56789 | '0.57' | '0.57' | '5.68e-01' | '56.79%' |
| 5.6789 | '5.7' | '5.68' | '5.68e+00' | '567.89%' |
| 56.789 | '5.7e+01' | '56.79' | '5.68e+01' | '5678.90%' |
+--------------+----------------+----------------+----------------+----------------+
'{<float>:g}'is'{<float>:.6}'with stripped zeros, exponent starting at'1e+06'.- When both rounding up and rounding down are possible, the one that returns result with even last digit is chosen. That makes
'{6.5:.0f}'a'6'and'{7.5:.0f}'an'8'. - This rule only effects numbers that can be represented exactly by a float (
.5,.25, …).
{90:c} # 'Z'
{90:b} # '1011010'
{90:X} # '5A'<int> = int(<float/str/bool>) # Or: math.floor(<float>)
<float> = float(<int/str/bool>) # Or: <int/float>e±<int>
<complex> = complex(real=0, imag=0) # Or: <int/float> ± <int/float>j
<Fraction> = fractions.Fraction(0, 1) # Or: Fraction(numerator=0, denominator=1)
<Decimal> = decimal.Decimal(<str/int>) # Or: Decimal((sign, digits, exponent))'int(<str>)'and'float(<str>)'raise ValueError on malformed strings.- Decimal numbers are stored exactly, unlike most floats where
'1.1 + 2.2 != 3.3'. - Floats can be compared with:
'math.isclose(<float>, <float>)'. - Precision of decimal operations is set with:
'decimal.getcontext().prec = <int>'.
<num> = pow(<num>, <num>) # Or: <num> ** <num>
<num> = abs(<num>) # <float> = abs(<complex>)
<num> = round(<num> [, ±ndigits]) # `round(126, -1) == 130`from math import e, pi, inf, nan, isinf, isnan # `<el> == nan` is always False.
from math import sin, cos, tan, asin, acos, atan # Also: degrees, radians.
from math import log, log10, log2 # Log can accept base as second arg.from statistics import mean, median, variance # Also: stdev, quantiles, groupby.from random import random, randint, choice # Also: shuffle, gauss, triangular, seed.
<float> = random() # A float inside [0, 1).
<int> = randint(from_inc, to_inc) # An int inside [from_inc, to_inc].
<el> = choice(<sequence>) # Keeps the sequence intact.<int> = ±0b<bin> # Or: ±0x<hex>
<int> = int('±<bin>', 2) # Or: int('±<hex>', 16)
<int> = int('±0b<bin>', 0) # Or: int('±0x<hex>', 0)
<str> = bin(<int>) # Returns '[-]0b<bin>'.<int> = <int> & <int> # And (0b1100 & 0b1010 == 0b1000).
<int> = <int> | <int> # Or (0b1100 | 0b1010 == 0b1110).
<int> = <int> ^ <int> # Xor (0b1100 ^ 0b1010 == 0b0110).
<int> = <int> << n_bits # Left shift. Use >> for right.
<int> = ~<int> # Not. Also -<int> - 1.import itertools as it>>> list(it.product([0, 1], repeat=3))
[(0, 0, 0), (0, 0, 1), (0, 1, 0), (0, 1, 1),
(1, 0, 0), (1, 0, 1), (1, 1, 0), (1, 1, 1)]>>> list(it.product('abc', 'abc')) # a b c
[('a', 'a'), ('a', 'b'), ('a', 'c'), # a x x x
('b', 'a'), ('b', 'b'), ('b', 'c'), # b x x x
('c', 'a'), ('c', 'b'), ('c', 'c')] # c x x x>>> list(it.combinations('abc', 2)) # a b c
[('a', 'b'), ('a', 'c'), # a . x x
('b', 'c')] # b . . x>>> list(it.combinations_with_replacement('abc', 2)) # a b c
[('a', 'a'), ('a', 'b'), ('a', 'c'), # a x x x
('b', 'b'), ('b', 'c'), # b . x x
('c', 'c')] # c . . x>>> list(it.permutations('abc', 2)) # a b c
[('a', 'b'), ('a', 'c'), # a . x x
('b', 'a'), ('b', 'c'), # b x . x
('c', 'a'), ('c', 'b')] # c x x .Provides 'date', 'time', 'datetime' and 'timedelta' classes. All are immutable and hashable.
# pip3 install python-dateutil
from datetime import date, time, datetime, timedelta, timezone
from dateutil.tz import tzlocal, gettz<D> = date(year, month, day) # Only accepts valid dates from 1 to 9999 AD.
<T> = time(hour=0, minute=0, second=0) # Also: `microsecond=0, tzinfo=None, fold=0`.
<DT> = datetime(year, month, day, hour=0) # Also: `minute=0, second=0, microsecond=0, …`.
<TD> = timedelta(weeks=0, days=0, hours=0) # Also: `minutes=0, seconds=0, microseconds=0`.- Aware
<a>time and datetime objects have defined timezone, while naive<n>don't. If object is naive, it is presumed to be in the system's timezone! 'fold=1'means the second pass in case of time jumping back for one hour.- Timedelta normalizes arguments to ±days, seconds (< 86 400) and microseconds (< 1M).
- Use
'<D/DT>.weekday()'to get the day of the week as an int, with Monday being 0.
<D/DTn> = D/DT.today() # Current local date or naive DT. Also DT.now().
<DTa> = DT.now(<tzinfo>) # Aware DT from current time in passed timezone.- To extract time use
'<DTn>.time()','<DTa>.time()'or'<DTa>.timetz()'.
<tzinfo> = timezone.utc # London without daylight saving time (DST).
<tzinfo> = timezone(<timedelta>) # Timezone with fixed offset from UTC.
<tzinfo> = tzlocal() # Local tz with dynamic offset. Also gettz().
<tzinfo> = gettz('<Continent>/<City>') # 'Continent/City_Name' timezone or None.
<DTa> = <DT>.astimezone([<tzinfo>]) # Converts DT to the passed or local fixed zone.
<Ta/DTa> = <T/DT>.replace(tzinfo=<tzinfo>) # Changes object's timezone without conversion.- Timezones returned by gettz(), tzlocal(), and implicit local timezone of naive objects have offsets that vary through time due to DST and historical changes of the zone's base offset.
- Standard library's zoneinfo.ZoneInfo() can be used instead of gettz() on Python 3.9 and later. It requires 'tzdata' package on Windows. It doesn't return local tz if arg. is omitted.
<D/T/DT> = D/T/DT.fromisoformat(<str>) # Object from ISO string. Raises ValueError.
<DT> = DT.strptime(<str>, '<format>') # Datetime from str, according to format.
<D/DTn> = D/DT.fromordinal(<int>) # D/DTn from days since the Gregorian NYE 1.
<DTn> = DT.fromtimestamp(<float>) # Local time DTn from seconds since the Epoch.
<DTa> = DT.fromtimestamp(<float>, <tz>) # Aware datetime from seconds since the Epoch.- ISO strings come in following forms:
'YYYY-MM-DD','HH:MM:SS.mmmuuu[±HH:MM]', or both separated by an arbitrary character. All parts following the hours are optional. - Python uses the Unix Epoch:
'1970-01-01 00:00 UTC','1970-01-01 01:00 CET', ...
<str> = <D/T/DT>.isoformat(sep='T') # Also `timespec='auto/hours/minutes/seconds/…'`.
<str> = <D/T/DT>.strftime('<format>') # Custom string representation of the object.
<int> = <D/DT>.toordinal() # Days since Gregorian NYE 1, ignoring time and tz.
<float> = <DTn>.timestamp() # Seconds since the Epoch, from DTn in local tz.
<float> = <DTa>.timestamp() # Seconds since the Epoch, from aware datetime.>>> dt = datetime.strptime('2025-08-14 23:39:00.00 +0200', '%Y-%m-%d %H:%M:%S.%f %z')
>>> dt.strftime("%dth of %B '%y (%a), %I:%M %p %Z")
"14th of August '25 (Thu), 11:39 PM UTC+02:00"'%z'accepts'±HH[:]MM'and returns'±HHMM'or empty string if datetime is naive.'%Z'accepts'UTC/GMT'and local timezone's code and returns timezone's name,'UTC[±HH:MM]'if timezone is nameless, or an empty string if datetime is naive.
<bool> = <D/T/DTn> > <D/T/DTn> # Ignores time jumps (fold attribute). Also ==.
<bool> = <DTa> > <DTa> # Ignores time jumps if they share tzinfo object.
<TD> = <D/DTn> - <D/DTn> # Ignores jumps. Convert to UTC for actual delta.
<TD> = <DTa> - <DTa> # Ignores time jumps if they share tzinfo object.
<D/DT> = <D/DT> ± <TD> # Returned datetime can fall into missing hour.
<TD> = <TD> * <int/float> # Also: <TD> = abs(<TD>) and <TD> = <TD> ±% <TD>.
<float> = <TD> / <TD> # How many weeks/years there are in TD. Also //.func(<positional_args>) # func(0, 0)
func(<keyword_args>) # func(x=0, y=0)
func(<positional_args>, <keyword_args>) # func(0, y=0)def func(<nondefault_args>): ... # def func(x, y): ...
def func(<default_args>): ... # def func(x=0, y=0): ...
def func(<nondefault_args>, <default_args>): ... # def func(x, y=0): ...- Default values are evaluated when function is first encountered in the scope.
- Any mutation of a mutable default value will persist between invocations!
Splat expands a collection into positional arguments, while splatty-splat expands a dictionary into keyword arguments.
args = (1, 2)
kwargs = {'x': 3, 'y': 4, 'z': 5}
func(*args, **kwargs)func(1, 2, x=3, y=4, z=5)Splat combines zero or more positional arguments into a tuple, while splatty-splat combines zero or more keyword arguments into a dictionary.
def add(*a):
return sum(a)>>> add(1, 2, 3)
6def f(*args): ... # f(1, 2, 3)
def f(x, *args): ... # f(1, 2, 3)
def f(*args, z): ... # f(1, 2, z=3)def f(**kwargs): ... # f(x=1, y=2, z=3)
def f(x, **kwargs): ... # f(x=1, y=2, z=3) | f(1, y=2, z=3)def f(*args, **kwargs): ... # f(x=1, y=2, z=3) | f(1, y=2, z=3) | f(1, 2, z=3) | f(1, 2, 3)
def f(x, *args, **kwargs): ... # f(x=1, y=2, z=3) | f(1, y=2, z=3) | f(1, 2, z=3) | f(1, 2, 3)
def f(*args, y, **kwargs): ... # f(x=1, y=2, z=3) | f(1, y=2, z=3)def f(*, x, y, z): ... # f(x=1, y=2, z=3)
def f(x, *, y, z): ... # f(x=1, y=2, z=3) | f(1, y=2, z=3)
def f(x, y, *, z): ... # f(x=1, y=2, z=3) | f(1, y=2, z=3) | f(1, 2, z=3)<list> = [*<coll.> [, ...]] # Or: list(<collection>) [+ ...]
<tuple> = (*<coll.>, [...]) # Or: tuple(<collection>) [+ ...]
<set> = {*<coll.> [, ...]} # Or: set(<collection>) [| ...]
<dict> = {**<dict> [, ...]} # Or: dict(**<dict> [, ...])head, *body, tail = <coll.> # Head or tail can be omitted.<func> = lambda: <return_value> # A single statement function.
<func> = lambda <arg_1>, <arg_2>: <return_value> # Also accepts default arguments.<list> = [i+1 for i in range(10)] # Or: [1, 2, ..., 10]
<iter> = (i for i in range(10) if i > 5) # Or: iter([6, 7, 8, 9])
<set> = {i+5 for i in range(10)} # Or: {5, 6, ..., 14}
<dict> = {i: i*2 for i in range(10)} # Or: {0: 0, 1: 2, ..., 9: 18}>>> [l+r for l in 'abc' for r in 'abc']
['aa', 'ab', 'ac', ..., 'cc']from functools import reduce<iter> = map(lambda x: x + 1, range(10)) # Or: iter([1, 2, ..., 10])
<iter> = filter(lambda x: x > 5, range(10)) # Or: iter([6, 7, 8, 9])
<obj> = reduce(lambda out, x: out + x, range(10)) # Or: 45<bool> = any(<collection>) # Is `bool(<el>)` True for any element.
<bool> = all(<collection>) # Is True for all elements or empty.<obj> = <exp> if <condition> else <exp> # Only one expression gets evaluated.>>> [a if a else 'zero' for a in (0, 1, 2, 3)] # `any([0, '', [], None]) == False`
['zero', 1, 2, 3]
