<p>我有以下测向:</p>
<pre><code>import pandas as pd
df = pd.DataFrame({'col1' : ["a","b"],
'col2' : ["ab","XX"], 'col3' : ["w","e"], 'col4':["foo","bar"]})
</code></pre>
<p>看起来像这样:</p>
^{pr2}$
<p>我要做的是将<code>col2, 3, 4</code>合并到一个名为<code>ID</code>的新列中</p>
<pre><code> col1 col2 col3 col4 ID
0 a ab w foo ab.w.foo
1 b XX e bar XX.e.bar
</code></pre>
<p>我怎么才能做到呢?在</p>
<p>我试过了,但失败了:</p>
<pre><code>df["ID"] = df.apply(lambda x: '.'.join(["col2","col3","col4"]),axis=1)
In [10]: df
Out[10]:
col1 col2 col3 col4 ID
0 a ab w foo col2.col3.col4
1 b XX e bar col2.col3.col4
</code></pre>