擅长:python、mysql、java
<p>这是另一种更紧凑的方法。在</p>
<pre><code>import csv
from collections import defaultdict
rows = defaultdict(set)
with open('in.csv') as f:
lines = csv.reader(f)
for line in lines:
rows[line[3].strip()].add((line[0],line[1],line[2]))
for key in rows:
print 'Total number of cars for %s is %s' % (key,len(rows[key]))
</code></pre>
<p>其结果是:</p>
^{pr2}$