<p><a href="https://i.stack.imgur.com/psmTm.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/psmTm.png" alt="enter image description here"/></a></p>
<p><a href="https://i.stack.imgur.com/3LnpC.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/3LnpC.png" alt="enter image description here"/></a></p>
<p>我尝试创建一个包含星期几的新列:</p>
<pre><code>df2019['Weekday']=pd.to_datetime(df2019['Year'],df2019['Month'],df2019['Day']).weekday()
</code></pre>
<p>我得到以下错误:</p>
<pre><code>ValueError: The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().
</code></pre>
<p>谢谢</p>