擅长:python、mysql、java
<p>使用<code>collections.defaultdict</code></p>
<pre><code>from collections import defaultdict
d_dict = defaultdict(dict)
for i in {k[0] for k in a}:
d_dict[i + 'only'] = {k:v for k,v in a.items() if k[0]==i}
print (dict(d_dict))
#{'conly': {'c1': 'obj_3', 'c2': 'obj_6'}, 'aonly': {'a1': 'obj_1', 'a2': 'obj_4'}, 'bonly': {'b1': 'obj_2', 'b2': 'obj_5'}}
</code></pre>