擅长:python、mysql、java
<h3><a href="https://pandas.pydata.org/pandas-docs/stable/generated/pandas.Series.nunique.html" rel="nofollow noreferrer">^{<cd1>}</a>+<a href="https://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.loc.html" rel="nofollow noreferrer">^{<cd2>}</a></h3>
<p>可以将<code>nunique</code>后跟<code>loc</code>与布尔索引一起使用:</p>
<pre><code>n = 5 # maximum number of unique values permitted
counts = app_train.select_dtypes(['object']).apply(pd.Series.nunique)
df = app_train.loc[:, ~app_train.columns.isin(counts[counts > n].index)]
# data from jezrael
print(df)
B C D E F
0 4 7 1 5 a
1 5 8 3 3 a
2 4 9 5 6 a
3 5 4 7 9 b
4 5 2 1 2 b
5 4 3 0 4 b
</code></pre>