apply same str format to df pandas code example

Example 1: formatting columns a dataframe python

import pandas as pd
df = pd.DataFrame([123.4567, 234.5678, 345.6789, 456.7890],
                  index=['foo','bar','baz','quux'],
                  columns=['cost'])
df['foo'] = df['cost']
df['cost'] = df['cost'].map('${:,.2f}'.format)
print(df)

Example 2: Pandas interpret cells as list

>>> from ast import literal_eval
>>> literal_eval('[1.23, 2.34]')
[1.23, 2.34]