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        在 Python 中使用范围作为字典键,我有什么选择?

        时间:2023-11-08
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                1. 本文介绍了在 Python 中使用范围作为字典键,我有什么选择?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着跟版网的小编来一起学习吧!

                  问题描述

                  这是我的第一篇文章,我对编程很陌生,所以我可能无法恰当地传达我的问题,但我会尽力而为!

                  This is my first post and I'm quite new at programming, so I might not be able to convey my question appropriately, but I'll do my best!

                  tries_dict = {1:'first', 2:'second', 3:'third', 4:'fourth', ub_tries:'last'}
                  
                  ub_tries = user input
                  
                  tries = 1
                  
                  input ('
                  Come on make your ' + tries_dict.get(tries) + guess: ')
                  

                  这 3 个元素是我创建的猜数游戏的一部分,我将它们包含在一个 while 循环中,其中 tries += 1 在每个错误答案之后.

                  These 3 elements are part of a number guess game I created, and I included them in a while loop where tries += 1 after each wrong answer.

                  如您所见,在我的字典中,前 4 个答案和游戏结束前最后可能的机会都有自定义值,所以这是我尝试做的:

                  As you can see, in my dictionary there are custom values for the first 4 answers and the last possible chance before the game is over, so here is what I tried to do:

                  我想找到一种方法,让第四"和最后"之间的每个答案/键都有NEXT"值.

                  I wanted to find a way to have the 'NEXT' value for every answer/key between 'fourth' and 'last'.

                  如:

                  tries = 5
                  
                  Come on make your next guess
                  
                  tries = 6
                  
                  Come on make your next guess
                  

                  等等

                  我确实找到了一些复杂循环的方法,但作为好奇的类型,我想知道更有效/实用的方法来完成这个.

                  I did find a way with some complex looping, but being the curious type I wanted to know of more efficient/practical ways to accomplish this.

                  以下是我想过但无法开始工作的一些选项:

                  Here are some options i thought about but couldn't get to work:

                  1. 使用范围作为键
                  2. 找到一种方法来生成一个值介于 4 和 ub_tries 之间的列表并将该列表用作键
                  1. Using a range as a key
                  2. Finding a way to generate a list with values between 4 and ub_tries and using that list as a key

                  一般来说:如何创建一种方法来为字典中未指定的键提供此一般答案(下一个或其他)?

                  So generally speaking: how can one create a way to have this general answer (next or whatever) for keys that aren't specified in a dictionary?

                  任何反馈都将不胜感激,请随时要求澄清,因为我可以告诉自己我的问题有点混乱.

                  Any feedback would be greatly appreciated, feel free to ask for clarifications since I can tell myself my question is kind of messy.

                  我希望我在编程和提出相关问题方面变得更加狡猾,到目前为止,我的编程几乎和我的总结技能一样混乱,叹息!

                  I hope I get more crafty both at programming and asking related questions, so far my programming is nearly as messy as my summary skills, sigh!

                  推荐答案

                  我不确定这是否是你想要的,但是 dict.get 可能是答案:

                  I'm not sure whether this is what you want, but dict.get may be the answer:

                  >>> ub_tries = 20
                  >>> tries_dict = {1:'first', 2:'second', 3:'third', 4:'fourth', ub_tries:'last'}
                  >>> tries_dict.get(1, 'next')
                  'first'
                  >>> tries_dict.get(4, 'next')
                  'fourth'
                  >>> tries_dict.get(5, 'next')
                  'next'
                  >>> tries_dict.get(20, 'next')
                  'last'
                  >>> tries_dict.get(21, 'next')
                  'next'
                  

                  当然,您可以以各种不同的方式将其封装在一个函数中.例如:

                  Of course you could wrap this up in a function, in various different ways. For example:

                  def name_try(try_number, ub_tries):
                      tries_dict = {1:'first', 2:'second', 3:'third', 4:'fourth', ub_tries:'last'}
                      return tries_dict.get(try_number, 'next')
                  

                  无论如何,dict.get(key, default=None) 类似于 dict[key],除了如果 key 是不是成员,而不是引发 KeyError,而是返回 default.

                  At any rate, dict.get(key, default=None) is like dict[key], except that if key is not a member, instead of raising a KeyError, it returns default.

                  至于你的建议:

                  使用范围作为键??

                  当然,您可以这样做(如果您使用的是 Python 2 而不是 3,请使用 xrange 表示 range),但它有什么帮助呢?

                  Sure, you can do that (if you're in Python 2 instead of 3, use xrange for range), but how would it help?

                  d = { range(1, 5): '???', 
                        range(5, ub_tries): 'next', 
                        range(ub_tries, ub_tries + 1): 'last' }
                  

                  这是完全合法的——但 d[6] 会引发 KeyError,因为 6 与 <代码>范围(5,ub_tries).

                  That's perfectly legal—but d[6] is going to raise a KeyError, because 6 isn't the same thing as range(5, ub_tries).

                  如果你想让它工作,你可以像这样构建一个 RangeDictionary:

                  If you want this to work, you could build a RangeDictionary like this:

                  class RangeDictionary(dict):
                      def __getitem__(self, key):
                          for r in self.keys():
                              if key in r:
                                  return super().__getitem__(r)
                          return super().__getitem__(key)
                  

                  但这远远超出了初学者的 Python",即使对于这种低效、不完整和不健壮的实现也是如此,所以我不建议这样做.

                  But that's well beyond "beginners' Python", even for this horribly inefficient, incomplete, and non-robust implementation, so I wouldn't suggest it.

                  找到一种方法来生成一个值在 4 到 ub_tries 之间的列表,并使用这样的列表作为键

                  finding a way to generate a list with values between 4 and ub_tries and using such list as a key

                  你的意思是这样的?

                  >>> ub_tries = 8
                  >>> tries_dict = {1:'first', 2:'second', 3:'third', 4:'fourth', ub_tries:'last'}
                  >>> tries_dict.update({i: 'next' for i in range(5, ub_tries)})
                  >>> tries_dict
                  {1: 'first', 2: 'second', 3: 'third', 4: 'fourth', 5: 'next', 6: 'next', 7: 'next', 8: 'last'}
                  >>> tries_dict[6]
                  'next'
                  

                  这可行,但它可能不是一个好的解决方案.

                  That works, but it's probably not as good a solution.

                  最后,您可以使用 defaultdict,它可以让您将默认值烘焙到字典中,而不是将其作为每次调用的一部分传递:

                  Finally, you could use defaultdict, which lets you bake the default value into the dictionary, instead of passing it as part of each call:

                  >>> from collections import defaultdict
                  >>> tries_dict = defaultdict(lambda: 'next', 
                  ...                          {1:'first', 2:'second', 3:'third', 4:'fourth', ub_tries:'last'})
                  >>> tries_dict
                  defaultdict(<function <lambda> at 0x10272fef0>, {8: 'last', 1: 'first', 2: 'second', 3: 'third', 4: 'fourth'})
                  >>> tries_dict[5]
                  'next'
                  >>> tries_dict
                  defaultdict(<function <lambda> at 0x10272fef0>, {1: 'first', 2: 'second', 3: 'third', 4: 'fourth', 5: 'next', 8: 'last'})
                  

                  但是,请注意,这会在您第一次请求时永久创建每个元素,并且您必须创建一个返回默认值的函数.这对于您要更新值并且只希望以默认值作为起点的情况更有用.

                  However, note that this permanently creates each element the first time you ask for it—and you have to create a function that returns the default value. This makes it more useful for cases where you're going to be updating values, and just want a default as a starting point.

                  这篇关于在 Python 中使用范围作为字典键,我有什么选择?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持跟版网!

                  上一篇:如何在 Python 中查找数字是否属于特定范围? 下一篇:使用 pandas 创建每小时/每分钟时间范围

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