擅长:python、mysql、java
<p>一种方法。不确定这是一个多么好的解决方案:</p>
<pre><code>df['Total_dl'] = df['Total_dl'].apply(lambda o: o if '<' in str(o) else np.nan)
</code></pre>
<p>改为使用执行相同操作的函数:</p>
<pre><code>>>> df
SampleID Total_dl
0 A-1-0' 2.5
1 A-1-0.5' <0.021
>>> df.dtypes
SampleID object
Total_dl object
dtype: object
>>> def foo(o):
... if '<' in str(o):
... return o
... else:
... return np.nan
...
>>> df['Total_dl'] = df['Total_dl'].apply(foo)
>>> df
SampleID Total_dl
0 A-1-0' NaN
1 A-1-0.5' <0.021
>>>
</code></pre>