擅长:python、mysql、java
<p>显然,这可以扩展到您的目的,但它执行一般操作时要记住:</p>
<pre><code>import math
for a in 'ABCD':
for b in 'ABCD':
count = 0
for x in document:
if a != b:
if a in x and b in x:
count += 1
else:
n = x.count(a)
if n >= 2:
count += math.factorial(n)/math.factorial(n - 2)/2
print '{} x {} = {}'.format(a, b, count)
</code></pre>