保存和加载列表值？

Question

I have a dataframe where one of the columns contains a list of values:

example: type(df['col_list'].values[0]) = list

I saved this dataframe as csv file ( df.to_csv('my_file.csv') )

When I load the dataframe ( df = pd.read_csv('my_file.csv') ) the column which contains list of values change to string type: type(df['col_list'].values[0]) = str

When converting to list ( list(df['col_list'].values[0] ) I'm getting list of characters instead of list of values.

How can I save/load dataframe which one of it's columns contains list of values?

Answer 1

Use JSON or HDF file format instead of CSV. CSV file format is really inconvenient for storing a list or a collection of objects.

Answer 2

This is due to the table being saved as CSV and serializing the values of the list. The csv format is unable to save the list object as it is. Try saving in another format df.to_pickle('test.df') . You can then read this back into a dataframe with read_pickle

Read more on saving to pickle here

Answer 3

I think Anurag's suggestion is very good. But just in case you want to keep things the way it is, this will do the job

import json
df['col_list'] = df['col_list'].apply(json.loads)

This would work better if you had converted col_list into JSON text before pd.to_csv by

df['col_list'] = df['col_list'].apply(json.dumps)