擅长:python、mysql、java
<p>首先<code>list</code>s的<a href="https://stackoverflow.com/questions/952914/making-a-flat-list-out-of-list-of-lists-in-python">flatten</a>值,然后按<a href="http://pandas.pydata.org/pandas-docs/stable/generated/pandas.Series.value_counts.html" rel="noreferrer">^{<cd2>}</a>或<a href="http://pandas.pydata.org/pandas-docs/stable/generated/pandas.core.groupby.GroupBy.size.html" rel="noreferrer">^{<cd3>}</a>或<code>Counter</code>计数:</p>
<pre><code>a = pd.Series([item for sublist in din.x for item in sublist])
</code></pre>
<p>或:</p>
<pre><code>a = pd.Series(np.concatenate(din.x))
</code></pre>
<hr/>
<pre><code>df = a.value_counts().sort_index().rename_axis('x').reset_index(name='f')
</code></pre>
<p>或:</p>
<pre><code>df = a.groupby(a).size().rename_axis('x').reset_index(name='f')
</code></pre>
<hr/>
<pre><code>from collections import Counter
from itertools import chain
df = pd.Series(Counter(chain(*din.x))).sort_index().rename_axis('x').reset_index(name='f')
print (df)
x f
0 a 2
1 b 1
2 c 2
3 d 1
4 e 1
</code></pre>