擅长:python、mysql、java
<p>使用:</p>
<pre><code>df = pd.DataFrame({'a':[1,2,3], 'b':[[{'width': 750, 'height': 498, 'url': 'https:/XXX'}], [{'width': 750, 'height': 498, 'url': 'https:/YYY'}], None]})
# df.dropna(inplace = True) #drop rows with null values
# to preserve rows with NaN, first replace NaN values with a scalar/dict value
df.fillna('null', inplace=True)
df['c'] = df['b'].apply(lambda x: [y['url'] if isinstance(x, list) else 'null' for y in x])
df['c'] = df['c'].apply(lambda x:x[0]) #get only the url from the list
#Output:
a b c
0 1 [{'width': 750, 'height': 498, 'url': 'https:/... https:/XXX
1 2 [{'width': 750, 'height': 498, 'url': 'https:/... https:/YYY
2 3 null null
</code></pre>