聪明的方法（1条通过你的列表）：

from collections import defaultdict

name_list = ["David Joyner", "David Zuber", "Brenton Joyner",
             "Brenton Zuber", "Nicol Barthel", "Shelba Barthel",
             "Shelba Crowley", "Shelba Fernald", "Shelba Odle",
             "Shelba Fry", "Maren Fry"]

rv = defaultdict(list)
for elem in name_list:
    rv[elem.split()[0]].append(elem) 

print(dict(rv))

输出：

{'David':  ['David Joyner', 'David Zuber'], 
 'Brenton':['Brenton Joyner', 'Brenton Zuber'], 
 'Nicol':  ['Nicol Barthel'], 
 'Shelba': ['Shelba Barthel','Shelba Crowley','Shelba Fernald','Shelba Odle','Shelba Fry'], 
 'Maren':  ['Maren Fry']}

慢速方式（可能看起来不错，但效率低下）：

d = {key:[n for n in name_list if n.startswith(key)] 
          for key in set( p.split()[0] for p in name_list)}

与defaultdict版本相比，这在计算上要差得多，因为它多次遍历列表：

• 一次创建set( p.split()[0] for p in name_list)
• 对于我们刚刚收集的每个名称，它会再次遍历完整列表以创建dict值 [n for n in name_list if n.startswith(key)]

如果你需要事后排序，只需list.sort()在dicts值上使用即可：

# sorting the data afterwards
for k in rv:
    rv[k].sort(key = lambda x:x.split()[1]) # to sort by last names

输出：

# only difference when sorted: see key `Shelba`
{'David':  ['David Joyner', 'David Zuber'], 
 'Brenton':['Brenton Joyner', 'Brenton Zuber'], 
 'Nicol':  ['Nicol Barthel'], 
 'Shelba': ['Shelba Barthel','Shelba Crowley','Shelba Fernald','Shelba Fry','Shelba Odle'], 
 'Maren':  ['Maren Fry']}