擅长:python、mysql、java
<p>您可以迭代<code>Food</code>对象列表,并更新过期时键入的字典,值为过期的项数。避免冗余,例如使用<code>collections.Counter</code>对象(dict的子类)在列表中保持零计数:</p>
<pre><code>from collections import Counter
d = Counter(food.expiration for food in fridge)
# fetch number of food with expiration 0
print(d[0]) # -> 0
# fetch number of food with expiration 1
print(d[1]) # -> 2
</code></pre>