如何将新元素添加到列表中的pandas.DataFrame列？

Question

我有pandas.DataFrame这样：

id       count        fruit_list
---------------------------------------
0        42           [orange, apple]
1        57           [lemon]
2        86           [kiwi]
3        33           [pineapple, pear]
4        11           [apple, lemon]
...

我需要在每行中向fruit_list添加新字符串。假设字符串为banana，所以我需要以DataFrame结尾：

id       count        fruit_list
---------------------------------------
0        42           [orange, apple, banana]
1        57           [lemon, banana]
2        86           [kiwi, banana]
3        33           [pineapple, pear, banana]
4        11           [apple, lemon, banana]
...

我怎样才能最轻松地做到这一点？

Answer 1

尝试apply：

df['fruit_list'] = df['fruit_list'].apply(lambda x: x + ['banana'])

样品：

df = pd.DataFrame({'count': [42, 57], 
                   'fruit_list': [['orange', 'apple'], ['lemon']], 
                   'id': [0, 1]}).reindex_axis(['id','count','fruit_list'], 1)
print (df)
   id  count       fruit_list
0   0     42  [orange, apple]
1   1     57          [lemon]

df['fruit_list'] = df['fruit_list'].apply(lambda x: x + ['banana'])
print (df)
   id  count               fruit_list
0   0     42  [orange, apple, banana]
1   1     57          [lemon, banana]