How to append a dataframe to an existing empty dataframe with a loop?

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)

zipa · Accepted Answer · 2018-02-01 15:56:15Z

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)

answered Feb 1, 2018 at 15:56

zipa

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1 Comment

KinWolf Over a year ago

Oh God , I did not even realize, thanks a lot zipa !

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