Halo, Habr! Saya sajikan kepada Anda terjemahan artikel "Tandai ini jika Anda baru menggunakan Python (terutama jika Anda belajar sendiri Python)" dalam dua bagian ( 1 , 2 ) dengan tips dan trik sederhana namun bermanfaat dalam Python.

- Python, . . , Python, , .. , Python . , Python , , .

: Python 3.8. - , , , Python.

>>> a = 1
>>> b = 3
>>> a == 1
True
>>> a == 2
False
>>> a == b
False
>>> a > b
False
>>> a <= b
True
>>> if a <= b :
...     print('a is less than or equal to b')
...
a is less than or equal to b

. True False. if-else.

>>> def compare(a,b):
...     if a> b:
...             return a
...     else:
...             return b
...

return.

>>> def compare(a, b):
...     return a if a > b else b
...

/

>>> arr_list = [1,4,7]
>>> a = arr_list[0]
>>> b = arr_list[1]
>>> c = arr_list[2]

, :

>>> a, b, c = arr_list
>>> a
1
>>> b
4
>>> c
7

>>> arr_list = [1,4,7]
>>> result = []
>>> for i in arr_list:
...     result.append(i*2)
...
>>> result
[2, 8, 14]

>>> result = [x*2 for x in arr_list]
>>> result
[2, 8, 14]

zip

>>> a = [1,5,8]
>>> b = [3,4,7]
>>> result = []
>>> for i in range(len(a)):
...     result.append(a[i] if a[i] < b[i] else b[i])
...
>>> result
[1, 4, 7]

>>> result = [min(i) for i in zip(a,b)]
>>> result
[1, 4, 7]

lambda

>>> arr_list= [[1,4], [3,3], [5,7]]
>>> arr_list.sort(key=lambda x: x[1])
>>> arr_list
[[3, 3], [1, 4], [5, 7]]

filter, map

>>> arr_list = [-1, 1, 3, 5]
>>> result = []
>>> for i in arr_list:
...     if i > 0:
...             result.append(i**2)
...
>>> result
[1, 9, 25]

>>> result = list(map(lambda x: x**2, filter(lambda x: x > 0, arr_list)))
>>> result
[1, 9, 25]

: -, :)

Oleg Kapustin Kuldeep Pal.

>>> result = [i**2 for i in arr_list if i > 0]
>>> result
[1, 9, 25]

,

set , , .

>>> arr_list = [1,4,4,6,9]
>>> len(arr_list) == len(set(arr_list))
False

>>> pi = 3.14159
#  Python3.6
>>> print('The value of pi is {:.2f}'.format(pi))
The value of pi is 3.14

>>> a, b, c = 1,5,9
>>> print('a is {}; b is {}; c is {}'.format(a,b,c))
a is 1; b is 5; c is 9

#  Python3.6+
>>> print(f'The value of pi is {pi:.2f}')
The value of pi is 3.14
>>> pi
3.14159

>>> print(f'a is {a}; b is {b}; c is {c}')
a is 1; b is 5; c is 9

: PyFormat

enumerate

>>> arr_list = [1, 5, 9]
>>> for i in range(len(arr_list)):
...     print(f'Index: {i}; Value: {arr_list[i]}')
...
Index: 0; Value: 1
Index: 1; Value: 5
Index: 2; Value: 9

>>> for i, j in enumerate(arr_list):
...     print(f'Index: {i}; Value: {j}')
...
Index: 0; Value: 1
Index: 1; Value: 5
Index: 2; Value: 9

>>> arr_list = [1,4,6,8,10,11]
>>> a, *b, c = arr_list
>>> a
1
>>> b
[4, 6, 8, 10]
>>> c
11

itertools

>>> str_list = ['A', 'C', 'F']
>>> list(itertools.combinations(str_list,2))
[('A', 'C'), ('A', 'F'), ('C', 'F')]
>>> list(itertools.permutations(str_list,2))
[('A', 'C'), ('A', 'F'), ('C', 'A'), ('C', 'F'), ('F', 'A'), ('F', 'C')]

>>> a = 5
>>> b = 8
>>> temp = a
>>> a = b
>>> b = temp + a
>>> a
8
>>> b
13

. .

>>> a = 5
>>> b = 8
>>> a,b = b, a+b
>>> a
8
>>> b
13

(PS: ? !)

: Evaluation order

>>> str_list = ['This', 'is', 'WYFok']
>>> ' '.join(str_list)
'This is WYFok'

, , join. .

>>> ans_list = [3,6,9]
>>> 'The answer is '+','.join(map(str,ans_list))
'The answer is 3,6,9'

map , join .

: str.join, map

Underscore ()

, , for, :

>>> for i in range(3):
...     print('Hello')
...
Hello
Hello
Hello

, i for. i _ (). ( _ – , Python . , .)

>>> for _ in range(3):
...     print('Hello')
...
Hello
Hello
Hello

Dict.keys, Dict.values, Dict.items

>>> teacher_subject = {'Ben':'English','Maria':'Math','Steve':'Science'}
>>> teacher_subject.keys()
dict_keys(['Ben', 'Maria', 'Steve'])
>>> teacher_subject.values()
dict_values(['English', 'Math', 'Science'])
>>> teacher_subject.items()
dict_items([('Ben', 'English'), ('Maria', 'Math'), ('Steve', 'Science')])

keys values . items , . , .

>>> subject_teacher = {y:x for x,y in teacher_subject.items()}
>>> subject_teacher
{'English': 'Ben', 'Math': 'Maria', 'Science': 'Steve'}

: , .

(: zip )

>>> subject = ['English','Math','Scienc']
>>> teacher = ['Ben','Maria','Steve']
>>> subject_teacher = {f:v for f,v in zip(subject,teacher)}
>>> subject_teacher
{'English': 'Ben', 'Math': 'Maria', 'Scienc': 'Steve'}

: Mapping Types — dict

>>> a = {1,2,3}
>>> b = {1,2,3,4,5}
# a  b?
>>> a<=b
True
# b  a?
>>> a>=b
False
#  a  b 
>>> a.union(b)
{1, 2, 3, 4, 5}
#  a  b 
>>> a.intersection(b)
{1, 2, 3}
#  
#    a,    b 
>>> a.difference(b)
set()
#    b,    a
>>> b.difference(a)
{4, 5}

: Set

collections.Counter

, . Counter, .

>>> import collections
>>> arr_list = [1,1,1,1,2,2,2,3,3,5,5,5,7]
>>> c = collections.Counter(arr_list)
>>> c
Counter({1: 4, 2: 3, 5: 3, 3: 2, 7: 1})
>>> type(c)
<class 'collections.Counter'>
>>> c[1]
4
>>> c[6]
0
#    
>>> dict(c)
{1: 4, 2: 3, 3: 2, 5: 3, 7: 1}

Informasi Tambahan: collections.Counter

Kesimpulan

Meskipun trik ini cukup sederhana, mereka dapat membantu menghemat waktu dan menyederhanakan kode Anda. Saya harap artikel ini membantu Anda mengetahui cara menggunakan fitur sederhana Python. Pelatihan dan kode yang bagus. Sampai jumpa lagi.

Tandai artikel ini jika Anda baru mengenal Python (terutama jika Anda mempelajari Python sendiri)

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zip