Appending pandas dataframes generated in a for loop

Question

I am accessing a series of Excel files in a for loop. I then read the data in the excel file to a pandas dataframe. I cant figure out how to append these dataframes together to then save the dataframe (now containing the data from all the files) as a new Excel file.

Here's what I tried:

for infile in glob.glob("*.xlsx"):

    data = pandas.read_excel(infile)

    appended_data = pandas.DataFrame.append(data) # requires at least two arguments

appended_data.to_excel("appended.xlsx")

Thanks!

Answer 1

Using pd.concat to merge a list of DataFrame into a single big DataFrame.

appended_data = []

for infile in glob.glob("*.xlsx"):

    data = pandas.read_excel(infile)

    # store DataFrame in list

    appended_data.append(data)

# see pd.concat documentation for more info

appended_data = pd.concat(appended_data)

# write DataFrame to an excel sheet 

appended_data.to_excel('appended.xlsx')

If you are interested to learn Pandas visit this Python Pandas Tutorial.