擅长:python、mysql、java
<p>根据<a href="https://docs.python.org/3.1/glossary.html" rel="nofollow noreferrer">this</a></p>
<blockquote>
<p><strong>hashable</strong></p>
<p>An object is hashable if it has a hash value which never changes during its lifetime (it needs a <strong>hash</strong>() method), and can be compared to other objects (it needs an <strong>eq</strong>() method). Hashable objects which compare equal must have the same hash value.</p>
<p>Hashability makes an object usable as a dictionary key and a set member, because these data structures use the hash value internally.</p>
<p>All of Python’s immutable built-in objects are hashable, while no mutable containers (such as lists or dictionaries) are. Objects which are instances of user-defined classes are hashable by default; they all compare unequal, and their hash value is their id().</p>
</blockquote>
<p>这意味着键不能是列表,这就是听写键()返回。所以你可以使用字典理解,就像我之前提到的。应该是这样的。你知道吗</p>
<pre><code> dictAvgGrade = {key: sum(values)/len(values) for key,values in studentPerf.items()}
</code></pre>
<p>这样就可以了。希望有帮助:)</p>