擅长:python、mysql、java
<pre class="lang-py prettyprint-override"><code># define a function which returns True if all are empty lists
all_empty = lambda x: all(not lst for lst in x)
# apply function to the two columns to create a mask
mask = df[['negative_keywords', 'positive_keywords']].apply(all_empty, axis=1)
# initialize the neutral_keywords column
df['neutral_keywords'] = [[]] * len(mask)
# update the neutral_keywords column where the mask is True
df.loc[mask, 'neutral_keywords'] = [['neutral']] * mask.sum()
df
</code></pre>