Karatasi ya Maelezo ya Python
Rejeleo linalotafutika na linaloweza kuchapishwa la Python 3 — sintaksia, miundo ya data, comprehensions, vitendakazi, klasi, mafaili na maktaba ya kawaida. Bila malipo.
Vigeu na aina
10x = 1
Pa kigeu thamani (aina inayobadilika)
x: int = 1
Annotation ya aina ya hiari
a, b = 1, 2
Upaji thamani wa pamoja
type(x)
Pata aina ya thamani
int('42')
Badilisha string kuwa integer
str(42)
Badilisha thamani kuwa string
isinstance(x, int)
Kagua aina
None
Thamani ya null/kutokuwepo
x = y = 0
Upaji thamani uliounganishwa
PI: Final = 3.14
Dokezo la const (typing.Final)
Strings
11f'Hello {name}'
Uwekaji ndani wa f-string
len(s)
Urefu wa string
s.upper()
Badilisha kuwa herufi kubwa
s.strip()
Ondoa nafasi zinazozunguka
s.split(',')
Gawanya kuwa list
','.join(items)
Unganisha list kwa kitenganishi
s.replace('a', 'b')
Badilisha substrings
'a' in s
Jaribio la uanachama
s[1:4]
Kata herufi 1 hadi 3
s[::-1]
Geuza string kinyume
s.startswith('a')
Angalia prefix
Lists na tuples
10a = [1, 2, 3]
Tengeneza list
a.append(4)
Ongeza kipengele mwishoni
a.insert(0, x)
Ingiza kwenye index
a.pop()
Ondoa na rudisha kipengele cha mwisho
a[1:3]
Kata sublist
sorted(a, reverse=True)
Rudisha nakala iliyopangwa
a.sort(key=len)
Panga papo hapo kwa key
len(a)
Idadi ya vipengele
t = (1, 2)
Tuple isiyobadilika
first, *rest = a
Fungua kwa nyota
Dicts na sets
10d = {'k': 'v'}
Tengeneza dictionary
d['k']
Fikia thamani kwa key
d.get('k', default)
Pata kwa fallback
d.keys() / d.values()
Tazama keys au thamani
d.items()
Pitia jozi za key/value
{**a, **b}
Unganisha dictionaries
a | b
Operator wa union wa dict/set
del d['k']
Ondoa key
s = {1, 2, 3}
Tengeneza set (thamani za kipekee)
set(a) & set(b)
Makutano ya set
Comprehensions
8[x * 2 for x in a]
List comprehension
[x for x in a if x > 0]
Comprehension iliyochujwa
{x: x**2 for x in a}
Dict comprehension
{x for x in a}
Set comprehension
(x for x in a)
Usemi wa generator (lazy)
[y for row in m for y in row]
Sambaza kwa loops zilizopachikwa
[a if c else b for x in items]
Thamani ya masharti kwenye comprehension
sum(x for x in a)
Kusanya generator
Mtiririko wa udhibiti
9if x > 0:\n ...
Masharti (indentation ni muhimu)
elif / else:
Matawi ya ziada
a if cond else b
Usemi wa ternary
for x in range(10):
Rudia juu ya range
for i, x in enumerate(a):
Rudia ukiwa na index
for a, b in zip(x, y):
Rudia iterables mbili pamoja
while cond:
Rudia mradi true
break / continue
Toka au ruka mzunguko
match x:\n case 1: ...
Mlinganisho wa muundo (3.10+)
Functions
8def f(a, b=1): return a + b
Function yenye argument chaguo-msingi
def f(*args, **kwargs):
Variadic positional + keyword args
f(name='Sam')
Ita kwa keyword argument
lambda x: x + 1
Function isiyo na jina ya inline
def f(a: int) -> int:
Dokezo za aina kwa params na return
@decorator
Funika function kwa decorator
yield value
Toa thamani kutoka generator
global x / nonlocal x
Funga upya kigeu cha wigo wa nje
Classes
9class A(Base):
Class yenye urithi
def __init__(self, x):
Constructor / initializer
self.x = x
Attribute ya instance
def __str__(self):
Uwakilishi wa string
@property
Attribute ya kusoma-tu iliyokokotolewa
@staticmethod / @classmethod
Static na class methods
super().__init__()
Ita initializer ya mzazi
@dataclass
Tengeneza otomatiki init/repr/eq
isinstance(obj, A)
Kagua aina ya instance
Files, makosa na modules
9with open('f.txt') as fh:
Fungua file (hufungwa otomatiki)
fh.read() / fh.readlines()
Soma yaliyomo kwenye file
open('f.txt', 'w').write(s)
Andika kwenye file
try:\n ...\nexcept ValueError as e:
Nasa exception mahususi
raise ValueError('bad')
Inua exception
finally:
Block ya usafishaji inayoendesha kila wakati
import os
Ingiza module
from math import sqrt
Ingiza jina mahususi
import numpy as np
Ingiza kwa alias
Hakuna kipengele kinacholingana na “:q”.
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