在python中按列表分类列表

Question

列表的示例列表:

[
["url","name","date","category"]
["hello","world","2010","one category"]
["foo","bar","2010","another category"]
["asdfasdf","adfasdf","2010","one category"]
["qwer","req","2010","another category"]
]

我想做的是创建一个字典 - >类别:[条目列表].

结果字典将是:

{"category" : [["url","name","date","category"]],
"one category" : [["hello","world","2010","one category"],["asdfasdf","adfasdf","2010","one category"]],
"another category" : [["foo","bar","2010","another category"], ["qwer","req","2010","another category"]]}

Answer 1

dict((category, list(l)) for category, l 
     in itertools.groupby(l, operator.itemgetter(3))

这里最重要的是使用itertools.groupby.它只是返回迭代而不是列表,这就是为什么有一个调用list(l),这意味着如果你对它有好处,你可以简单地写dict(itertools.groupby(l, operator.itemgetter(3)))

Answer 2

newdict = collections.defaultdict(list)
for entry in biglist:
  newdict[entry[3]].append(entry)