擅长:python、mysql、java
<p>不需要计数器:只需抓取<code>split</code>ing之后的最后一个标记,并计算第一个和最后一个字符:</p>
<pre><code>first_counter = {}
last_counter = {}
for line in f:
line=line.split()[-1] # grab the last token
first_counter[line[0]] = first_counter.get(line[0], 0) + 1
last_counter[line[-1]] = last_counter.get(line[-1], 0) + 1
print("first ", first_counter)
print("last ", last_counter)
</code></pre>
<p><strong>输出</strong></p>
<pre><code>first {'P': 1, 'N': 1}
last {'V': 2}
</code></pre>