1.檢查重復元素

下面的方法可以檢查給定列表中是否有重復的元素。它使用了 set() 屬性，該屬性將會從列表中刪除重復的元素。

def all_unique(lst): return len(lst) == len(set(lst)) x = [1,1,2,2,3,2,3,4,5,6] y = [1,2,3,4,5] all_unique(x) # False all_unique(y) # True

2.變位詞

檢測兩個字符串是否互為變位詞（即互相顛倒字符順序）

from collections import Counter def anagram(first, second): return Counter(first) == Counter(second) anagram("abcd3", "3acdb") # True

3.檢查內存使用情況

import sys variable = 30 print(sys.getsizeof(variable)) # 24

4.字節大小計算

以下方法將以字節為單位返回字符串長度。

def byte_size(string): return(len(string.encode( utf-8 ))) byte_size( 😀 ) # 4 byte_size( Hello World ) # 11

5.重復打印字符n次

n = 2; s ="Programming"; print(s * n); # ProgrammingProgramming

6.首字母大寫

s = "programming is awesome" print(s.title()) # Programming Is Awesome

7.分塊

from math import ceil def chunk(lst, size): return list( map(lambda x: lst[x * size:x * size + size], list(range(0, ceil(len(lst) / size))))) chunk([1,2,3,4,5],2) # [[1,2],[3,4],5]

8.壓縮

以下方法使用 fliter() 刪除列表中的錯誤值（如：False, None, 0 和“”）

def compact(lst): return list(filter(bool, lst)) compact([0, 1, False, 2, , 3, a , s , 34]) # [ 1, 2, 3, a , s , 34 ]

9.間隔數

以下代碼段可以用來轉換一個二維數組。

array = [[ a , b ], [ c , d ], [ e , f ]] transposed = zip(*array) print(transposed) # [( a , c , e ), ( b , d , f )]

10.鏈式比較

以下代碼可以在一行中用各種操作符進行多次比較。

a = 3 print( 2 < a < 8) # True print(1 == a < 2) # False

11.逗號分隔

hobbies = ["basketball", "football", "swimming"] print("My hobbies are: " + ", ".join(hobbies)) # My hobbies are: basketball, football, swimming

12.計算元音字母數

import re def count_vowels(str): return len(len(re.findall(r [aeiou] , str, re.IGNORECASE))) count_vowels( foobar ) # 3 count_vowels( gym ) # 0

13.首字母恢復小寫

def decapitalize(string): return str[:1].lower() + str[1:] decapitalize( FooBar ) # fooBar decapitalize( FooBar ) # fooBar

14.平面化

以下方法使用遞歸來展開潛在的深度列表。

def spread(arg):ret = []for i in arg:if isinstance(i, list):ret.extend(i)else:ret.append(i)return ret def deep_flatten(lst):result = []result.extend(spread(list(map(lambda x: deep_flatten(x) if type(x) == list else x, lst))))return result deep_flatten([1, [2], [[3], 4], 5]) # [1,2,3,4,5]

15.差異

def difference(a, b):set_a = set(a)set_b = set(b)comparison = set_a.difference(set_b)return list(comparison) difference([1,2,3], [1,2,4]) # [3]

16.尋找差異

def difference_by(a, b, fn):b = set(map(fn, b))return [item for item in a if fn(item) not in b] from math import floor difference_by([2.1, 1.2], [2.3, 3.4],floor) # [1.2] difference_by([{ x : 2 }, { x : 1 }], [{ x : 1 }], lambda v : v[ x ]) # [ { x: 2 } ]

17.鏈式函數調用

def add(a, b):return a + b def subtract(a, b):return a - b a, b = 4, 5 print((subtract if a > b else add)(a, b)) # 9

18.檢查重復元素

def has_duplicates(lst):return len(lst) != len(set(lst))x = [1,2,3,4,5,5] y = [1,2,3,4,5] has_duplicates(x) # True has_duplicates(y) # False

19.合并兩個字典

def merge_two_dicts(a, b):c = a.copy() # make a copy of a c.update(b) # modify keys and values of a with the ones from breturn c a = { x : 1, y : 2} b = { y : 3, z : 4} print(merge_two_dicts(a, b)) # { y : 3, x : 1, z : 4} #在python3.5版本后你還可以： def merge_dictionaries(a, b)return {**a, **b} a = { x : 1, y : 2} b = { y : 3, z : 4} print(merge_dictionaries(a, b)) # { y : 3, x : 1, z : 4}

20.將兩個列表轉化成一個字典

def to_dictionary(keys, values):return dict(zip(keys, values))keys = ["a", "b", "c"] values = [2, 3, 4] print(to_dictionary(keys, values)) # { a : 2, c : 4, b : 3}

21.使用枚舉

以下方法將字典作為輸入，然后僅返回該字典中的鍵。 list = ["a", "b", "c", "d"] for index, element in enumerate(list): print("Value", element, "Index ", index, ) # ( Value , a , Index , 0) # ( Value , b , Index , 1) #( Value , c , Index , 2) # ( Value , d , Index , 3)

22.計算需要的時間

import time start_time = time.time() a = 1 b = 2 c = a + b print(c) #3 end_time = time.time() total_time = end_time - start_time print("Time: ", total_time) # ( Time: , 1.1205673217773438e-05)

23.Try else指令

你可以將 else 子句作為 try/except 塊的一部分，如果沒有拋出異常，則執行該子句。

try:2*3 except TypeError:print("An exception was raised") else:print("Thank God, no exceptions were raised.") #Thank God, no exceptions were raised.

24.查找最常見元素

以下方法返回列表中出現的最常見元素。

def most_frequent(list):return max(set(list), key = list.count)list = [1,2,1,2,3,2,1,4,2] most_frequent(list)

25.回文

以下方法可檢查給定的字符串是否為回文結構。該方法首先將字符串轉換為小寫，然后從中刪除非字母數字字符。最后，它會將新的字符串與反轉版本進行比較。

def palindrome(string):from re import subs = sub( [W_] , , string.lower())return s == s[::-1] palindrome( taco cat ) # True

26.沒有 if-else 語句的簡單計算器

import operator action = {"+": operator.add,"-": operator.sub,"/": operator.truediv,"*": operator.mul,"**": pow } print(action[ - ](50, 25)) # 25

27.元素順序打亂

from copy import deepcopy from random import randint def shuffle(lst):temp_lst = deepcopy(lst)m = len(temp_lst)while (m):m -= 1i = randint(0, m)temp_lst[m], temp_lst[i] = temp_lst[i], temp_lst[m]return temp_lstfoo = [1,2,3] shuffle(foo) # [2,3,1] , foo = [1,2,3]

28.列表扁平化

def spread(arg):ret = []for i in arg:if isinstance(i, list):ret.extend(i)else:ret.append(i)return ret spread([1,2,3,[4,5,6],[7],8,9]) # [1,2,3,4,5,6,7,8,9]

29.變量變換

def swap(a, b):return b, a a, b = -1, 14 swap(a, b) # (14, -1)

30.獲取確實鍵的默認值

d = { a : 1, b : 2} print(d.get( c , 3)) # 3

總結

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