熊猫数据框-具有重组数据的新数据框

Question

I'm new to Pandas and trying to create a new dataframe from an existing one.

My current dataframe has a format:

ID   Country    Status  
ABC  USA        Go
ABC  Columbia   Stop
ABC  Japan      Pause
ABC  Egypt      Go 
DEF  Canada     Go
DEF  Peru       Stop

I'm trying to consolidate the data to make it more compact. My new format is:

ID   Go          Stop      Pause
ABC  USA, Egypt  Columbia  Japan
DEF  Canada      Peru

Basically, the possible Status values become the columns and, for each ID, these columns are populated with a list of countries having that status. I'm new to pandas and struggling with the best way to approach this - any suggestions would be greatly appreciated.

Answer 1

You can use pd.pivot_table :

res = df.pivot_table(index='ID', columns='Status', values='Country', aggfunc=', '.join)

print(res)

Status          Go  Pause      Stop
ID                                 
ABC     USA, Egypt  Japan  Columbia
DEF         Canada   None      Peru

Answer 2

If you absolutely must do this then this is how you do it.

In [48]: df.groupby(['ID', 'Status'])['Country'].apply(','.join).unstack()
Out[48]:
Status         Go  Pause      Stop
ID
ABC     USA,Egypt  Japan  Columbia
DEF        Canada    NaN      Peru