Msingi wa Python

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Msingi wa Python

Taarifa muhimu

list(xrange()) == range() --> Katika python3 range ni xrange ya python2 (siyo orodha bali ni jenereta)
Tofauti kati ya Tuple na Orodha ni kwamba nafasi ya thamani katika tuple inampa maana lakini orodha ni thamani zilizopangwa tu. Tuples zina muundo lakini orodha zina mpangilio.

Operesheni kuu

Ili kuinua nambari unatumia: 3**2 (siyo 3^2)
Ikiwa unafanya 2/3 inarudisha 1 kwa sababu unagawa ints mbili (nambari nzima). Ikiwa unataka desimali unapaswa kugawa floats (2.0/3.0).
i >= j
i <= j
i == j
i != j
a na b
a au b
siyo a
float(a)
int(a)
str(d)
ord("A") = 65
chr(65) = 'A'
hex(100) = '0x64'
hex(100)[2:] = '64'
isinstance(1, int) = True
"a b".split(" ") = ['a', 'b']
" ".join(['a', 'b']) = "a b"
"abcdef".startswith("ab") = True
"abcdef".contains("abc") = True
"abc\n".strip() = "abc"
"apbc".replace("p","") = "abc"
dir(str) = Orodha ya mbinu zote zinazopatikana
help(str) = Maelezo ya darasa str
"a".upper() = "A"
"A".lower() = "a"
"abc".capitalize() = "Abc"
sum([1,2,3]) = 6
sorted([1,43,5,3,21,4])

Unganisha wahusika
3 * ’a’ = ‘aaa’
‘a’ + ‘b’ = ‘ab’
‘a’ + str(3) = ‘a3’
[1,2,3]+[4,5]=[1,2,3,4,5]

Sehemu za orodha
‘abc’[0] = ‘a’
'abc’[-1] = ‘c’
'abc’[1:3] = ‘bc’ kutoka [1] hadi [2]
"qwertyuiop"[:-1] = 'qwertyuio'

Maoni
# Maoni ya mstari mmoja
"""
Maoni ya mistari kadhaa
Mwingine
"""

Mizunguko

if a:
#somethig
elif b:
#something
else:
#something

while(a):
#comething

for i in range(0,100):
#something from 0 to 99

for letter in "hola":
#something with a letter in "hola"

Tuples

t1 = (1,'2,'three')
t2 = (5,6)
t3 = t1 + t2 = (1, '2', 'three', 5, 6)
(4,) = Singelton
d = () tuple tupu
d += (4,) --> Kuongeza kwenye tuple
CANT! --> t1[1] == 'New value'
list(t2) = [5,6] --> Kutoka tuple hadi orodha

List (array)

d = [] tupu
a = [1,2,3]
b = [4,5]
a + b = [1,2,3,4,5]
b.append(6) = [4,5,6]
tuple(a) = (1,2,3) --> Kutoka orodha hadi tuple

Dictionary

d = {} tupu
monthNumbers={1:’Jan’, 2: ‘feb’,’feb’:2}—> monthNumbers ->{1:’Jan’, 2: ‘feb’,’feb’:2}
monthNumbers[1] = ‘Jan’
monthNumbers[‘feb’] = 2
list(monthNumbers) = [1,2,’feb’]
monthNumbers.values() = [‘Jan’,’feb’,2]
keys = [k for k in monthNumbers]
a={'9':9}
monthNumbers.update(a) = {'9':9, 1:’Jan’, 2: ‘feb’,’feb’:2}
mN = monthNumbers.copy() #Nakala huru
monthNumbers.get('key',0) #Angalia kama ufunguo upo, Rudisha thamani ya monthNumbers["key"] au 0 kama haipo

Set

Katika set hakuna kurudiwa
myset = set(['a', 'b']) = {'a', 'b'}
myset.add('c') = {'a', 'b', 'c'}
myset.add('a') = {'a', 'b', 'c'} #Hakuna kurudiwa
myset.update([1,2,3]) = set(['a', 1, 2, 'b', 'c', 3])
myset.discard(10) #Kama ipo, iondoe, kama sio, hakuna kitu
myset.remove(10) #Kama ipo iondoe, kama sio, inua exception
myset2 = set([1, 2, 3, 4])
myset.union(myset2) #Thamani ni myset AU myset2
myset.intersection(myset2) #Thamani katika myset NA myset2
myset.difference(myset2) #Thamani katika myset lakini sio katika myset2
myset.symmetric_difference(myset2) #Thamani ambazo hazipo katika myset NA myset2 (sio katika zote)
myset.pop() #Pata kipengele cha kwanza cha set na uondoe
myset.intersection_update(myset2) #myset = Vipengele katika myset na myset2
myset.difference_update(myset2) #myset = Vipengele katika myset lakini sio katika myset2
myset.symmetric_difference_update(myset2) #myset = Vipengele ambavyo havipo katika zote

Classes

Njia katika __It__ itakuwa ile itakayotumika na sort kulinganisha kama kitu cha darasa hili ni kikubwa kuliko kingine

class Person(name):
def __init__(self,name):
self.name= name
self.lastName = name.split(‘ ‘)[-1]
self.birthday = None
def __It__(self, other):
if self.lastName == other.lastName:
return self.name < other.name
return self.lastName < other.lastName #Return True if the lastname is smaller

def setBirthday(self, month, day. year):
self.birthday = date tame.date(year,month,day)
def getAge(self):
return (date time.date.today() - self.birthday).days


class MITPerson(Person):
nextIdNum = 0	# Attribute of the Class
def __init__(self, name):
Person.__init__(self,name)
self.idNum = MITPerson.nextIdNum  —> Accedemos al atributo de la clase
MITPerson.nextIdNum += 1 #Attribute of the class +1

def __it__(self, other):
return self.idNum < other.idNum

ramani, zip, filter, lambda, sorted na one-liners

Map ni kama: [f(x) kwa x katika iterable] --> map(tutple,[a,b]) = [(1,2,3),(4,5)]
m = map(lambda x: x % 3 == 0, [1, 2, 3, 4, 5, 6, 7, 8, 9]) --> [False, False, True, False, False, True, False, False, True]

zip inasimama wakati mfupi wa foo au bar unaposimama:

for f, b in zip(foo, bar):
print(f, b)

Lambda inatumika kufafanua kazi
(lambda x,y: x+y)(5,3) = 8 --> Tumia lambda kama kazi
sorted(range(-5,6), key=lambda x: x** 2) = [0, -1, 1, -2, 2, -3, 3, -4, 4, -5, 5] --> Tumia lambda kupanga orodha
m = filter(lambda x: x % 3 == 0, [1, 2, 3, 4, 5, 6, 7, 8, 9]) = [3, 6, 9] --> Tumia lambda kuchuja
reduce (lambda x,y: x*y, [1,2,3,4]) = 24

def make_adder(n):
return lambda x: x+n
plus3 = make_adder(3)
plus3(4) = 7 # 3 + 4 = 7

class Car:
crash = lambda self: print('Boom!')
my_car = Car(); my_car.crash() = 'Boom!'

mult1 = [x for x in [1, 2, 3, 4, 5, 6, 7, 8, 9] if x%3 == 0 ]

Mifanozo

def divide(x,y):
try:
result = x/y
except ZeroDivisionError, e:
print “division by zero!” + str(e)
except TypeError:
divide(int(x),int(y))
else:
print “result i”, result
finally
print “executing finally clause in any case”

Assert()

Ikiwa hali si ya kweli, maandiko yataonyeshwa kwenye skrini.

def avg(grades, weights):
assert not len(grades) == 0, 'no grades data'
assert len(grades) == 'wrong number grades'

Generators, yield

Generator, badala ya kurudisha kitu, "hutoa" kitu. Unapokifikia, kitarejesha thamani ya kwanza iliyozalishwa, kisha, unaweza kukifikia tena na kitarejesha thamani inayofuata iliyozalishwa. Hivyo, thamani zote hazizalishwi kwa wakati mmoja na kumbukumbu nyingi zinaweza kuokolewa kwa kutumia hii badala ya orodha yenye thamani zote.

def myGen(n):
yield n
yield n + 1

g = myGen(6) --> 6
next(g) --> 7
next(g) --> Hitilafu

Mifumo ya Kawaida

import re
re.search("\w","hola").group() = "h"
re.findall("\w","hola") = ['h', 'o', 'l', 'a']
re.findall("\w+(la)","hola caracola") = ['la', 'la']

Maana maalum:
. --> Kila kitu
\w --> [a-zA-Z0-9_]
\d --> Nambari
\s --> Karakteri ya Nafasi[ \n\r\t\f]
\S --> Karakteri isiyo na nafasi
^ --> Anza na
$ --> Maliza na
+ --> Moja au zaidi
* --> 0 au zaidi
? --> Matukio 0 au 1

Chaguzi:
re.search(pat,str,re.IGNORECASE)
IGNORECASE
DOTALL --> Ruhusu nukta kuendana na newline
MULTILINE --> Ruhusu ^ na $ kuendana katika mistari tofauti

re.findall("<.*>", "<b>foo</b>and<i>so on</i>") = ['<b>foo</b>and<i>so on</i>']
re.findall("<.*?>", "<b>foo</b>and<i>so on</i>") = ['<b>', '</b>', '<i>', '</i>']

IterTools
product
from itertools import product --> Inazalisha mchanganyiko kati ya orodha 1 au zaidi, labda ikirudia thamani, bidhaa ya Cartesian (mali ya usambazaji)
print list(product([1,2,3],[3,4])) = [(1, 3), (1, 4), (2, 3), (2, 4), (3, 3), (3, 4)]
print list(product([1,2,3],repeat = 2)) = [(1, 1), (1, 2), (1, 3), (2, 1), (2, 2), (2, 3), (3, 1), (3, 2), (3, 3)]

permutations
from itertools import permutations --> Inazalisha mchanganyiko wa wahusika wote katika kila nafasi
print list(permutations(['1','2','3'])) = [('1', '2', '3'), ('1', '3', '2'), ('2', '1', '3'),... Mchanganyiko wote wa uwezekano
print(list(permutations('123',2))) = [('1', '2'), ('1', '3'), ('2', '1'), ('2', '3'), ('3', '1'), ('3', '2')] Mchanganyiko wote wa urefu 2

combinations
from itertools import combinations --> Inazalisha mchanganyiko wote wa uwezekano bila kurudia wahusika (ikiwa "ab" ipo, haiwezi kuunda "ba")
print(list(combinations('123',2))) --> [('1', '2'), ('1', '3'), ('2', '3')]

combinations_with_replacement
from itertools import combinations_with_replacement --> Inazalisha mchanganyiko wote wa uwezekano kuanzia wahusika (kwa mfano, ya tatu inachanganywa kuanzia ya tatu lakini si na ya pili au ya kwanza)
print(list(combinations_with_replacement('1133',2))) = [('1', '1'), ('1', '1'), ('1', '3'), ('1', '3'), ('1', '1'), ('1', '3'), ('1', '3'), ('3', '3'), ('3', '3'), ('3', '3')]

Wapambo

Mwapambo unaopima muda ambao kazi inahitaji kutekelezwa (kutoka hapa):

from functools import wraps
import time
def timeme(func):
@wraps(func)
def wrapper(*args, **kwargs):
print("Let's call our decorated function")
start = time.time()
result = func(*args, **kwargs)
print('Execution time: {} seconds'.format(time.time() - start))
return result
return wrapper

@timeme
def decorated_func():
print("Decorated func!")

Ikiwa utaikimbiza, utaona kitu kama ifuatavyo:

Let's call our decorated function
Decorated func!
Execution time: 4.792213439941406e-05 seconds