列表格式的熊猫数据框列值

Question

For some reason, one of my dataframe column is filled with lists as its value.

(ex): "Book Date" - [01/20/2018]

I've tried to make it into a string by applying both str(x) and ''.join(x) method but it doesn't work.

df['Book Date'] = df['Book Date'].map(lambda x: ''.join(x))

Could you please let me know what I should do and how to avoid this in the first place?
Thank you in advance!

Answer 1

Use apply + join() and map() in order to convert your list to strings first.

Example DataFrame:

  >>> df1
      Book Date
1  [01/20/2018]
2  [01/22/2018]

Result:

>>> df1['Book Date'].apply(lambda x: ','.join(map(str, x)))
1    01/20/2018
2    01/22/2018
Name: Book Date, dtype: object

OR

You could convert your list to str with astype(str) and then use replace to remove [ ] & ' .

>>> df1['Book Date'].astype(str).str.replace('\[|\]|\'', '')
1    01/20/2018
2    01/22/2018
Name: Book Date, dtype: object