擅长:python、mysql、java
<p>没有<code>collections.Counter</code>:</p>
<pre><code>import collections
sentence = "A long sentence may contain repeated letters"
count = collections.defaultdict(int) # save some time with a dictionary factory
for letter in sentence: # iterate over each character in the sentence
count[letter] += 1 # increase count for each of the sentences
</code></pre>
<p>或者如果您真的想完全手动执行:</p>
^{pr2}$
<p>在这两种情况下,<code>count</code>字典将以每个不同的字母作为其键,其值将是遇到一个字母的次数,例如:</p>
^{3}$
<p>如果您希望它不区分大小写,请确保在将其添加到计数时调用<code>letter.lower()</code>。在</p>