好用的Python技巧 一篇文章带你了解几个好用的Python技巧

keys_list = ['A', 'B', 'C'] 
values_list = ['blue', 'red', 'bold'] 
# 有 3 种方法可以将这两个列表转换为字典 
# 1.使用Python zip、dict函数 
dict_method_1 = dict(zip(keys_list, values_list)) 
# 2. 使用带有字典推导式的 zip 函数 
dict_method_2 = {key:value for key, value in zip(keys_list, values_list)} 
# 3.循环使用zip函数 
items_tuples = zip(keys_list, values_list)  
dict_method_3 = {}  
for key, value in items_tuples:  
    if key in dict_method_3:  
        pass  
    else:  
        dict_method_3[key] = value 
print(dict_method_1) 
print(dict_method_2) 
print(dict_method_3) 

def merge(*args, missing_val = None): 
    max_length = max([len(lst) for lst in args]) 
    outList = [] 
    for i in range(max_length): 
        outList.append([args[k][i] if i < len(args[k]) else missing_val for k in range(len(args))]) 
    return outList 
merge([1,2,3],['a','b','c'],['h','e','y'],[4,5,6]) 

dicts_lists = [ 
  { 
    "Name": "James", 
    "Age": 20, 
  }, 
  { 
     "Name": "May", 
     "Age": 14, 
  }, 
  { 
    "Name": "Katy", 
    "Age": 23, 
  } 
] 
# 方法一 
dicts_lists.sort(key=lambda item: item.get("Age")) 
# 方法二 
from operator import itemgetter 
f = itemgetter('Name') 
dicts_lists.sort(key=f) 

my_list = ["blue", "red", "green"] 
# 方法一 
my_list.sort()  
my_list = sorted(my_list, key=len)  
# 方法二 
import locale 
from functools import cmp_to_key 
my_list = sorted(my_list, key=cmp_to_key(locale.strcoll))  

a = ['blue', 'green', 'orange', 'purple', 'yellow'] 
b = [3, 2, 5, 4, 1] 
sortedList =  [val for (_, val) in sorted(zip(b, a), key=lambda x: x[0])] 
print(sortedList) 

mylist = ['blue', 'orange', 'green'] 
#Map the list into a dict using the map, zip and dict functions 
mapped_dict = dict(zip(itr, map(fn, itr))) 

from collections import defaultdict 
def merge_dicts(*dicts): 
    mdict = defaultdict(list) 
    for dict in dicts: 
    for key in dict: 
        res[key].append(d[key]) 
    return dict(mdict) 

my_dict = { 
  "brand": "Ford", 
  "model": "Mustang", 
  "year": 1964 
} 
# 方法一 
my_inverted_dict_1 = dict(map(reversed, my_dict.items())) 
# 方法二 
from collections import defaultdict 
my_inverted_dict_2 = defaultdict(list) 
{my_inverted_dict_2[v].append(k) for k, v in my_dict.items()} 
print(my_inverted_dict_1) 
print(my_inverted_dict_2) 

str_val = 'books' 
num_val = 15 
print(f'{num_val} {str_val}')  
print(f'{num_val % 2 = }')  
print(f'{str_val!r}')  
price_val = 5.18362 
print(f'{price_val:.2f}')  
from datetime import datetime; 
date_val = datetime.utcnow() 
print(f'{date_val=:%Y-%m-%d}')  

addresses = ["123 Elm Street", "531 Oak Street", "678 Maple Street"] 
street = "Elm Street" 
# 方法一 
for address in addresses: 
    if address.find(street) >= 0: 
        print(address) 
# 方法二 
for address in addresses: 
    if street in address: 
        print(address) 

str1 = "hello" 
str2 = "" 
def str_size(s): 
    return len(s.encode('utf-8')) 
print(str_size(str1)) 
print(str_size(str2)) 

# 方法一 
import os  
exists = os.path.isfile('/path/to/file') 
# 方法二 
from pathlib import Path 
config = Path('/path/to/file')  
if config.is_file():  
    pass 

import csv 
csv_mapping_list = [] 
with open("/path/to/data.csv") as my_data: 
    csv_reader = csv.reader(my_data, delimiter=",") 
    line_count = 0 
    for line in csv_reader: 
        if line_count == 0: 
            header = line 
        else: 
            row_dict = {key: value for key, value in zip(header, line)} 
            csv_mapping_list.append(row_dict) 
        line_count += 1