Python pandas - merge csv files in directory into one

问题

I have a directory with csv files:

frames/df1.csv
       df2.csv

frames are structured like this:

df1.csv

               artist            track        plays
1            Pearl Jam           Jeremy         456
2   The Rolling Stones   Heart of Stone         546

df2.csv

                artist            track        likes
3            Pearl Jam           Jeremy         5673
9   The Rolling Stones   Heart of Stone         3456

and I would like to merge all frames into one, ending up with:

              artist            track          plays       likes    
0          Pearl Jam           Jeremy            456        5673       
1 The Rolling Stones   Heart of Stone            546        3456       

I've tried:

path = 'frames'
all_files = glob.glob(path + "/*.csv")
list_ = []
for file_ in all_files:
    df = pd.read_csv(file_,index_col=None, header=0)
    list_.append(df)
frame = pd.concat(list_)

to no avail. what is the best way to approach this?

回答1:

I just simply using your code create the list of DataFrame

path = 'frames'
all_files = glob.glob(path + "/*.csv")
l= []
for file_ in all_files:
    df = pd.read_csv(file_,index_col=None, header=0)
    l.append(df)

Then using functools.reduce, merge the list dataframe into one

import functools
l= [df1, df2, df3....]
merged_df = functools.reduce(lambda left,right: pd.merge(left,right,on=['artist','track']), l)

回答2:

DataFrame.join is useful. Its analogous to a SQL join. Something like:

df1.join(df2, on=('artist', 'track'))

来源：https://stackoverflow.com/questions/46751699/python-pandas-merge-csv-files-in-directory-into-one