Python - 创建一个字典，以键为第一个字符，值作为以该字符开头的单词

在本文中，我们将编写一个Python程序来创建一个字典，以键为第一个字符，值为以该字符开头的单词。

Python中的Dictionary是一个无序的数据值集合，用于像map一样存储数据值，与其他Data Types只保存单个值作为元素不同，Dictionary保存着key: value对。字典中提供了键值，以使其更加优化。

例子：

Input: Hello World
Output: {'H': ['Hello'], 
         'W': ['World']}

Input: Welcome to GeeksForGeeks
Output: {'W': ['Welcome'], 
         't': ['to'], 
         'G': ['GeeksForGeeks']}

方法：

• 我们将字符串保存在一个变量中并声明一个空字典。
• 然后我们将字符串拆分为单词并形成这些单词的列表。
• 对于每个单词，我们将检查该单词的关键字是否存在。
• 如果不是，那么我们将把那个键和词添加到字典中，如果它已经存在，那么我们会将该词附加到该键的子列表中。

下面是上述方法的实现：

Python3

# Python program to Create a Dictionary with Key as First
# Character and Value as Words Starting with that Character
  
# Driver Code
  
# Declaring String Data
string_input = '''GeeksforGeeks is a Computer Science  portal for geeks.
       It contains well written, well thought and well explained
       computer science and programming articles, quizzes etc.'''
  
# Storing words in the input as a list
words = string_input.split()
  
# Declaring empty dictionary
dictionary = {}
  
for word in words:
  
    # If key is not present in the dictionary then we
    # will add the key and word to the dictionary.
    if (word[0] not in dictionary.keys()):
  
        # Creating a sublist to store words with same
        # key value and adding it to the list.
        dictionary[word[0]] = []
        dictionary[word[0]].append(word)
  
    # If key is present then checking for the word
    else:
  
        # If word is not present in the sublist then
        # adding it to the sublist of the proper key
        # value
        if (word not in dictionary[word[0]]):
            dictionary[word[0]].append(word)
  
# Printing the dictionary
print(dictionary)

输出：

{'G': ['GeeksforGeeks'], 
 'i': ['is'], 
 'a': ['a', 'and', 'articles,'], 
 'C': ['Computer'],
 'S': ['Science'], 
 'p': ['portal', 'programming'], 
 'f': ['for'], 
 'g': ['geeks.'], 
 'I': ['It'], 
 'c': ['contains', 'computer'], 
 'w': ['well', 'written,'], 
 't': ['thought'],
 'e': ['explained', 'etc.'], 
 's': ['science'], 
 'q': ['quizzes']}

您可以看到在上面程序的输出中，以G开头的单词有两个键“ G ”和“ g ”，因此为了消除该问题并使代码不区分大小写，我们将使用Python中的lower()函数。我们将用小写保存所有键，这样无论何时我们检查键时，以“ G ”和“ g ”开头的单词都将位于同一个键下。下面是实现：

蟒蛇3

# Python program to Create a Dictionary with Key as First
# Character and Value as Words Starting with that Character
  
# Driver Code
  
# Declaring String Data
string_input = '''GeeksforGeeks is a Computer Science  portal for geeks.
       It contains well written, well thought and well explained
       computer science and programming articles, quizzes etc.'''
  
# Storing words in the input as a list
words = string_input.split()
  
# Declaring empty dictionary
dictionary = {}
  
for word in words:
  
    # If key is not present in the dictionary then we
    # will add the key and word to the dictionary.
    if (word[0].lower() not in dictionary.keys()):
  
        # Creating a sublist to store words with same
        # key value and adding it to the list.
        dictionary[word[0].lower()] = []
        dictionary[word[0].lower()].append(word)
  
    # If key is present then checking for the word
    else:
  
        # If word is not present in the sublist then
        # adding it to the sublist of the proper key
        # value
        if (word not in dictionary[word[0].lower()]):
            dictionary[word[0].lower()].append(word)
  
# Printing the dictionary
print(dictionary)

输出：

{'g': ['GeeksforGeeks', 'geeks.'],
 'i': ['is', 'It'],
 'a': ['a', 'and', 'articles,'], 
 'c': ['Computer', 'contains', 'computer'], 
 's': ['Science', 'science'], 
 'p': ['portal', 'programming'], 
 'f': ['for'], 
 'w': ['well', 'written,'], 
 't': ['thought'], 
 'e': ['explained', 'etc.'], 
 'q': ['quizzes']}