Python collections.defaultdict()

两个代码例子

import collectionss = [('yellow', 1), ('blue', 2), ('yellow', 3), ('blue', 4), ('red', 1)]d = collections.defaultdict(list)for k, v in s:    print k, v    d[k].append(v)print dprint list(d.items())

import collectionss = [('yellow', 1), ('blue', 2), ('yellow', 3), ('blue', 4), ('red', 1)]# defaultdictd = collections.defaultdict(list)for k, v in s:    d[k].append(v)# Use dict and setdefault   g = {}for k, v in s:    g.setdefault(k, []).append(v)# Use dicte = {}for k, v in s:    e[k] = v##list(d.items())##list(g.items())##list(e.items())