如何映射到词典

Question

所以我有一个清单看起来是这样的：

[['hostile', 'angry'], ['elated', 'happy'], ['elated', 'grateful'], ['depressed', 'sad']]

由此产生：

c.execute("""SELECT category, wordlist from wordtest order by category""")
                categoryfile = c.fetchall()
                categoryfile = [list(x) for x in categoryfile]

我希望category的所有值都合并到一个键中，然后wordlist中与该类别配对的所有单词都合并到一个列表中。有可能吗？你知道吗

所以最终，有了这个列表，你会看到

['elated', 'happy'], ['elated', 'grateful']

变成：

{'elated': ['happy', 'grateful']}

Answer 1

使用collections.defaultdict：

from collections import defaultdict

myList = [['hostile', 'angry'], ['elated', 'happy'], ['elated', 'grateful'], ['depressed', 'sad']]  

myDict = defaultdict(list)

for key, value in myList:
    myDict[key].append(value)

Answer 2

lis=[['hostile', 'angry'], ['elated', 'happy'], ['elated', 'grateful'], ['depressed', 'sad']]
dic={}
for x in lis:
    dic.setdefault(x[0],[]).append(x[1])
print dic   

输出：

{'depressed': ['sad'], 'elated': ['happy', 'grateful'], 'hostile': ['angry']}