<p>您可以使用<a href="https://docs.python.org/3/library/stdtypes.html#dict.setdefault" rel="nofollow noreferrer">setdefault</a>:</p>
<pre><code>item_list = [['Boots of Speed', 50],
['Health Potion', 60],
['Health Potion', 80],
['Dorans Blade', 120],
['Dorans Ring', 180],
['Dorans Blade', 200],
['Dorans Ring', 210]]
result = {}
for item, count in item_list:
result.setdefault(item, []).append(count)
print([[key, sum(value) / len(value) ] for key, value in result.items()])
</code></pre>
<p>或者从collections模块使用<a href="https://docs.python.org/3/library/collections.html#collections.defaultdict" rel="nofollow noreferrer">defaultdict</a>:</p>
<pre><code>from collections import defaultdict
item_list = [['Boots of Speed', 50],
['Health Potion', 60],
['Health Potion', 80],
['Dorans Blade', 120],
['Dorans Ring', 180],
['Dorans Blade', 200],
['Dorans Ring', 210]]
result = defaultdict(list)
for item, count in item_list:
result[item].append(count)
print([[key, sum(value) / len(value) ] for key, value in result.items()])
</code></pre>
<p><strong>输出</strong></p>
<pre><code>[['Dorans Blade', 160.0], ['Boots of Speed', 50.0], ['Health Potion', 70.0], ['Dorans Ring', 195.0]]
</code></pre>