擅长:python、mysql、java
<pre><code>Class Person:
def __init__(self):
self.samples = { year: { sample: 0 for sample in ('a', 'b') } for year in (2017,2018,2019) }
def add_to(self, year, sample):
self.samples[year][sample] += 1
instance = Person()
instance.add_to(2017, 'b')
</code></pre>