通过字符串循环时，将多个值添加到字典 [英] Adding more than one value to dictionary when looping through string

问题描述

仍然超新到Python 3，遇到一个问题...我正在尝试创建一个函数，它返回一个字典，其中键是每个单词的长度，值是字符串中的单词。

Still super new to Python 3 and have encountered a problem... I am trying to create a function which returns a dictionary with the keys being the length of each word and the values being the words in the string.

例如，如果我的字符串是：狗很快前进到公园，我的字典应该返回
{2 ：['to'] 3：['''，'run'，'the']，4：['dogs'，'park]，7：['快速'，'转发']}

For example, if my string is: "The dogs run quickly forward to the park", my dictionary should return {2: ['to'] 3: ['The', 'run', 'the'], 4: ['dogs', 'park], 7: ['quickly', 'forward']}

问题是当我循环浏览项目时，它只是在字符串中附加一个单词。

Problem is that when I loop through the items, it is only appending one of the words in the string.

def word_len_dict(my_string):
    dictionary = {}
    input_list = my_string.split(" ")
    unique_list = []
    for item in input_list:
        if item.lower() not in unique_list:
            unique_list.append(item.lower())
    for word in unique_list:
        dictionary[len(word)] = []
        dictionary[len(word)].append(word)
    return (dictionary)

print (word_len_dict("The dogs run quickly forward to the park"))

代码返回

{2: ['to'], 3: ['run'], 4: ['park'], 7: ['forward']}

有人可以指出我的方向吗？也许不能自由地给我答案，但是下面我需要看一下将缺少的单词添加到列表中。我认为将它们附加到列表中会做到这一点，但不是这样。

Can someone point me in the right direction? Perhaps not giving me the answer freely, but what do I need to look at next in terms of adding the missing words to the list. I thought that appending them to the list would do it, but it's not.

谢谢！

推荐答案

这将解决您的所有问题：

This will solve all your problems:

def word_len_dict(my_string):
    input_list = my_string.split(" ")

    unique_set = set()
    dictionary = {}

    for item in input_list:
        word = item.lower()
        if word not in unique_set:
            unique_set.add(word)
            key = len(word)
            if key not in dictionary:
                dictionary[key] = []
            dictionary[key].append(word)

    return dictionary

您每次遇到时都会擦除dict条目一个新词还有一些有效的问题（在成长期间搜索成员名单，为O（n）任务产生O（n ** 2）个算法。更换成员资格考试清单成员资格考试更正了效率问题。

You were wiping dict entries each time you encountered a new word. There were also some efficiencly problems (searching a list for membership while growing it resulted in an O(n**2) algorithm for an O(n) task). Replacing the list membership test with a set membership test corrected the efficiency problem.

为您的示例句子提供正确的输出：

It gives the correct output for your sample sentence:

>>> print(word_len_dict("The dogs run quickly forward to the park"))
{2: ['to'], 3: ['the', 'run'], 4: ['dogs', 'park'], 7: ['quickly', 'forward']}

我注意到其他一些发布的解决方案无法将单词映射为小写和/或无法删除重复的内容，这显然是您想要的。

I noticed some of the other posted solutions are failing to map words to lowercase and/or failing to remove duplicates, which you clearly wanted.

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