如何通过循环将数据框追加到现有的空数据框？

Question

I want to fill an empty dataframe with data in csv files by using a loop. The code works fine except that each time the dataframe records only the last csv file and not all the csv files that exist in the destination folder.

Did I do something wrong?

Here is a piece of my code :

csv_files = glob.glob(path +"/*.csv")

for csv_file in csv_files:

     columns_name = [A,B,C,D]
     newDF = pd.DataFrame( columns=columns_name)
     newDF = pd.concat([newDF,df])
     newDF.fillna('unknown', inplace=True)

Answer 1

Just move newDF outside the loop:

csv_files = glob.glob(path +"/*.csv")

columns_name = [A,B,C,D]
newDF = pd.DataFrame( columns=columns_name)

for csv_file in csv_files:
     newDF = pd.concat([newDF,df])
     newDF.fillna('unknown', inplace=True)