擅长:python、mysql、java
<p>使用<a href="https://pandas.pydata.org/pandas-docs/stable/generated/pandas.Categorical.html" rel="nofollow noreferrer">^{<cd1>}</a>可以指定类别列表:</p>
<pre><code>In [44]: cats = a[['A','B']].stack().sort_values().unique()
In [45]: cats
Out[45]: array(['a', 'b', 'c'], dtype=object)
In [46]: a['A'] = pd.Categorical(a['A'], categories=cats)
In [47]: a['B'] = pd.Categorical(a['B'], categories=cats)
In [48]: a[cat_columns] = a[cat_columns].apply(lambda x: x.cat.codes)
In [49]: a
Out[49]:
A B
0 1 2
1 1 2
2 0 2
3 1 0
4 0 0
</code></pre>