Question

在将值添加到现有键值方面一直遇到问题。

这是我的代码：

mydict = {}

def assemble_dictionary(filename):
   file = open(filename,'r')
   for word in file:
       word = word.strip().lower() #makes the word lower case and strips any unexpected chars
       firstletter = word[0]
       if firstletter in mydict.keys():
           continue
       else:
           mydict[firstletter] = [word]

   print(mydict)

assemble_dictionary('try.txt')

try.txt包含几个词-Ability，Absolute，Butterfly，Cloud。因此Ability和Absolute应该在同一键下，但是我找不到能使我这样做的函数。类似于

mydict[n].append(word)

其中n是行号。

此外，有没有一种方法可以轻松地定位字典中的值数量？

当前输出=

{'a': ['ability'], 'b': ['butterfly'], 'c': ['cloud']}

但我希望成为

{'a': ['ability','absolute'], 'b': ['butterfly'], 'c': ['cloud']}

Answer 1

选项1：

当检查字典中是否已存在键时，可以添加append语句。

mydict = {}

def assemble_dictionary(filename):
   file = open(filename,'r')
   for word in file:
       word = word.strip().lower() #makes the word lower case and strips any unexpected chars
       firstletter = word[0]
       if firstletter in mydict.keys():
           mydict[firstletter].append(word)
       else:
           mydict[firstletter] = [word]

   print(mydict)

选项2：您可以使用dict setDefault使用默认值初始化dict，以防不存在密钥，然后附加该项。

mydict = {}

def assemble_dictionary(filename):
    file = open(filename,'r')
        for word in file:
            word = word.strip().lower() #makes the word lower case and strips any unexpected chars
            firstletter = word[0]
            mydict.setdefault(firstletter,[]).append(word)
    print(mydict)

Answer 2

您可以简单地将单词附加到现有键上：

def assemble_dictionary(filename):
   with open(filename,'r') as f:
       for word in f:
           word = word.strip().lower() #makes the word lower case and strips any unexpected chars
           firstletter = word[0]
           if firstletter in mydict.keys():
               mydict[firstletter].append(word)
           else:
               mydict[firstletter] = [word]

输出：

{'a': ['ability', 'absolute'], 'b': ['butterfly'], 'c': ['cloud']}

另外（与问题无关），最好使用with语句打开文件，使用完该文件也将其关闭。

Answer 3

您可以通过这种方式实现

mydict = {}
a = ['apple', 'abc', 'b', 'c']
for word in a:
    word = word.strip().lower() #makes the word lower case and strips any unexpected chars
    firstletter = word[0]
    if firstletter in mydict.keys():
        values = mydict[firstletter] # Get the origial values/words 
        values.append(word) # Append new word to the list of words
        mydict[firstletter] = values
    else:
        mydict[firstletter] = [word]

print(mydict)

Outout：

{'a': ['apple', 'abc'], 'c': ['c'], 'b': ['b']}

Answer 4

mydict [firstletter] = [word]，替换值

由于密钥采用列表格式，请尝试

mydict[firstletter].extend(word)

将值添加到字典键

4 个答案: