This question already has an answer here: What does ** (double star/asterisk) and * (star/asterisk) do for parameters? 15 answers The syntax is the * and ** . The names *args and **kwargs are only by convention but there's no hard requirement to use them. You would use *args when you're not sure how many arguments might be passed to your function, ie it allows you pass an arbitrar
这个问题在这里已经有了答案： **（双星/星号）和*（星号/星号）对参数做什么？ 15个答案 语法是*和** 。 名字*args和**kwargs只是惯例，但没有硬性要求使用它们。 当你不确定有多少参数可能传递给你的函数时，你会使用*args ，即它允许你传递任意数量的参数给你的函数。 例如： >>> def print_everything(*args): for count, thing in enumerate(args): ... print( '{0}. {1}'.format(count,
I have a dictionary of values read from two fields in a database: a string field and a numeric field. The string field is unique, so that is the key of the dictionary. I can sort on the keys, but how can I sort based on the values? Note: I have read Stack Overflow question How do I sort a list of dictionaries by values of the dictionary in Python? and probably could change my code to have a
我有一个从数据库中的两个字段中读取值的字典：一个字符串字段和一个数字字段。 字符串字段是唯一的，所以这是字典的关键。 我可以对键进行排序，但是如何根据这些值进行排序？ 注意：我已阅读Stack Overflow问题如何按Python中字典的值对字典列表进行排序？ 并可能可以改变我的代码有一个字典的列表，但因为我真的不需要一个字典的列表，我想知道是否有一个更简单的解决方案。 为了完整起见，我使用heapq发布了一个解决
Assume that I have a dict. data = {1:'b', 2:'a'} And I want to sort data by 'b' and 'a' so I get the result 'a','b' How do I do that? Any ideas? To get the values use sorted(data.values()) To get the matching keys, use a key function sorted(data, key=data.get) To get a list of tuples ordered by value sorted(data.items(), key=lambda x:x[1]) Related: see the discussion
假设我有一个字典。 data = {1:'b', 2:'a'} 我想按'b'和'a'排序数据，以便得到结果 'a','b' 我怎么做？ 有任何想法吗？ 获取值使用 sorted(data.values()) 要获得匹配的键，请使用key功能 sorted(data, key=data.get) 获取按值排序的元组列表 sorted(data.items(), key=lambda x:x[1]) 相关内容：请参阅此处的讨论：字典以Python 3.6+订购 如果你真的想对字典进行排序而不是仅仅获得一个排序列表
I'm iterating over a list of tuples in Python, and am attempting to remove them if they meet certain criteria. for tup in somelist: if determine(tup): code_to_remove_tup What should I use in place of code_to_remove_tup ? I can't figure out how to remove the item in this fashion. You can use a list comprehension to create a new list containing only the elements you don
我遍历Python中的元组列表，并试图在符合特定条件时将其删除。 for tup in somelist: if determine(tup): code_to_remove_tup 我应该用什么来代替code_to_remove_tup ？ 我无法弄清楚如何以这种方式去除物品。 您可以使用列表理解来创建一个仅包含您不想删除的元素的新列表： somelist = [x for x in somelist if not determine(x)] 或者，通过分配片段somelist[:] ，可以对现有列表进行变异以仅包含所需的
I want to generate a string of size N. It should be made up of numbers and uppercase English letters such as: 6U1S75 4Z4UKK U911K4 How can I achieve this in a pythonic way? Answer in one line: ''.join(random.choice(string.ascii_uppercase + string.digits) for _ in range(N)) or even shorter starting with Python 3.6 using random.choices() : ''.join(random.choices(string.ascii_uppercas
我想要生成一个大小为N的字符串 它应该由数字和大写英文字母组成，例如： 6U1S75 4Z4UKK U911K4 我怎样才能以pythonic的方式实现这一点？ 一行回答： ''.join(random.choice(string.ascii_uppercase + string.digits) for _ in range(N)) 或者使用random.choices()从Python 3.6开始更短： ''.join(random.choices(string.ascii_uppercase + string.digits, k=N)) 密码更安全的版本; 请参阅https://stackoverflo
How can I generate random integers between 0 and 9 (inclusive) in Python? ie 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 Try: from random import randint print(randint(0, 9)) More info: https://docs.python.org/3/library/random.html#random.randint import random print(random.randint(0,9)) random.randint(a, b) Return a random integer N such that a <= N <= b. Docs: https://docs.python.org/3.
我如何在Python中生成0到9（含）之间的随机整数？ 即0 ， 1 ， 2 ， 3 ， 4 ， 5 ， 6 ， 7 ， 8 ， 9 尝试： from random import randint print(randint(0, 9)) 更多信息：https：//docs.python.org/3/library/random.html#random.randint import random print(random.randint(0,9)) random.randint(a, b) 返回一个随机整数N，使得a <= N <= b。 文档：https：//docs.python.org/3.1/library/random.html#rando
When trying to delete a key from a dictionary, I write: if 'key' in myDict: del myDict['key'] Is there a one line way of doing this? Use dict.pop() : my_dict.pop('key', None) This will return my_dict[key] if key exists in the dictionary, and None otherwise. If the second parameter is not specified (ie. my_dict.pop('key') ) and key does not exist, a KeyError is raised. Specifi
当试图从字典中删除密钥时，我写道： if 'key' in myDict: del myDict['key'] 有没有一种方法可以做到这一点？ 使用dict.pop() ： my_dict.pop('key', None) 如果key存在于字典中，这将返回my_dict[key] ，否则返回None 。 如果未指定所述第二参数（即my_dict.pop('key')和key不存在，一个KeyError上升。 具体回答“是否有一条这样做的路线？” if 'key' in myDict: del myDict['key'] ...好吧，你问了;-)
Imagine that you have: keys = ('name', 'age', 'food') values = ('Monty', 42, 'spam') What is the simplest way to produce the following dictionary ? a_dict = {'name' : 'Monty', 'age' : 42, 'food' : 'spam'} This code works, but I'm not really proud of it : a_dict = {} junk = map(lambda k, v: a_dict.update({k: v}), keys, values) Like this: >>> keys = ['a', 'b', 'c'] >>>
想象一下，你有： keys = ('name', 'age', 'food') values = ('Monty', 42, 'spam') 生成下列字典最简单的方法是什么？ a_dict = {'name' : 'Monty', 'age' : 42, 'food' : 'spam'} 此代码有效，但我并不为此感到自豪： a_dict = {} junk = map(lambda k, v: a_dict.update({k: v}), keys, values) 喜欢这个： >>> keys = ['a', 'b', 'c'] >>> values = [1, 2, 3] >>> dictionary = dict(zip(k
Is it possible to add a key to a Python dictionary after it has been created? It doesn't seem to have an .add() method. >>> d = {'key':'value'} >>> print(d) {'key': 'value'} >>> d['mynewkey'] = 'mynewvalue' >>> print(d) {'mynewkey': 'mynewvalue', 'key': 'value'} >>> x = {1:2} >>> print x {1: 2} >>> x.update({3:4}) >>>
是否可以在创建Python字典后添加一个键？ 它似乎没有.add()方法。 >>> d = {'key':'value'} >>> print(d) {'key': 'value'} >>> d['mynewkey'] = 'mynewvalue' >>> print(d) {'mynewkey': 'mynewvalue', 'key': 'value'} >>> x = {1:2} >>> print x {1: 2} >>> x.update({3:4}) >>> print x {1: 2, 3: 4} 我觉得整理有关Python字典的信息： 创建
Does anyone know how the built in dictionary type for python is implemented? My understanding is that it is some sort of hash table, but I haven't been able to find any sort of definitive answer. Here is everything about Python dicts that I was able to put together (probably more than anyone would like to know; but the answer is comprehensive). Python dictionaries are implemented as hash
有谁知道python的内置字典类型是如何实现的？ 我的理解是它是某种散列表，但我一直没能找到任何明确的答案。 以下是我能够放在一起的所有Python字典（可能比任何人都想知道的更多;但答案是全面的）。 Python字典被实现为散列表 。 散列表必须允许散列冲突，即使两个不同的键具有相同的散列值，表的实现也必须具有明确插入和检索键和值对的策略。 Python dict使用开放寻址来解决散列冲突（如下所述）（请参阅dictobject.