分享一些非常实用的Python小技巧

x = [1,1,2,2,3,2,3,4,5,6] y = [1,2,3,4,5] len(x)== len(set(x)) # False len(y)== len(set(y)) # True 

from collections import Counter >>> Counter('abadfsdafsdfjsdaf') Counter({'a': 4, 'd': 4, 'f': 4, 's': 3, 'b': 1, 'j': 1}) def anagram(first, second): return Counter(first) == Counter(second) anagram("abcd3", "3acdb") # True 

import sys variable = 30 print(sys.getsizeof(variable)) # 28 

print(len(''.encode('utf-8')))# 0 print(len('hellow sdfsdaf'.encode('utf-8'))) # 14 

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

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

>>> list = list(range(12)) >>> size=3 >>> [list[i:i+size] for i in range(0,len(list), size)] [[0, 1, 2], [3, 4, 5], [6, 7, 8], [9, 10, 11]] >>> 

list(filter(bool, [0, 1, False, 2, '', 3, 'a', 's', 34])) 

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

a = 3 print( 2 

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

import re print(len(re.findall(r'[aeiou]', 'foobar', re.IGNORECASE)))   # 3 print(len(re.findall(r'[aeiou]', 'gym', re.IGNORECASE)))   # 0 

'FooBar'[:1].lower() + 'FooBar'[1:] # 'fooBar' 'FooBar'[:1].lower() + 'FooBar'[1:]   # 'fooBar' 

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] print(deep_flatten([1, [2], [[3], 4], 5]))  # [1,2,3,4,5] 

set([1,2,3])-set([1,2,4]) # [3] 

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 } ] 

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 

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} 

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

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

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

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

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

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] print(spread([1, 2, 3, [4, 5,[10,11,12,132,4,[1,2,3,4,5,6]], 6], [7], 8, 9]))  #[1, 2, 3, 4, 5, [10, 11, 12, 132, 4, [1, 2, 3, 4, 5, 6]], 6, 7, 8, 9]