将字符串转换为列表

Question

I have a data frame like

query
-----------
[]
[(apple,10),(orange,15)]
[(apple,2),(orange,5)]

python is reading this as a string instead of a list because when I do df['query'].apply(lambda x: len(x)) I get 2 instead of 0 for the first row. Is there a way to convert this to a list.

Answer 1

You can use apply() :

df['query'] = df['query'].apply(lambda x: x.strip('[]').split(','))

os, by list comprehension:

df['query'] = [x.strip('[]').split(',') for x in df['query']]

or, use ast.literal_eval() :

import ast
df['query'] = df['query'].apply(lambda x: ast.literal_eval(x))

or,

df['query'] = df['query'].apply(ast.literal_eval)