擅长:python、mysql、java
<p>将<a href="http://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.Series.value_counts.html" rel="nofollow noreferrer">^{<cd1>}</a>与<code>date</code>列一起用于<code>Series</code>与{a2}或<a href="http://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.core.groupby.GroupBy.size.html" rel="nofollow noreferrer">^{<cd5>}</a>:</p>
<pre><code>df = pd.DataFrame({'date':pd.to_datetime(['2019-10-10','2019-10-10','2019-10-09']),
'col1':['a','b','c']})
s = df['date'].value_counts().sort_index()
#alternative
#s = df.groupby('date').size()
</code></pre>
<hr/>
^{pr2}$
<p>最后一次使用<a href="http://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.Series.plot.html" rel="nofollow noreferrer">^{<cd6>}</a>:</p>
<pre><code>s.plot()
</code></pre>