how to list all files in folders into an excel sheet

Question

I am trying to list all files in folders into excel worksheet. The code I wrote can generate the result in the image attached (top one, but rows are not indexed), but I would like to have it formatted to the image at the bottom. How can I do that with python? Thanks!

import os
import pandas as pd
alist=[]
blist=[]
for folderName,subfolders,filenames in os.walk(r'C:\Users\2020'):
  alist.append(filenames)
  blist.append(str(folderName))
print(alist)
print(blist)

res_dct = {blist[i]: alist[i] for i in range(0, len(blist))} 

df=pd.DataFrame.from_dict(res_dct,orient='index')

Answer 1

Given the DataFrame:

df = pd.DataFrame({
    0: ['File1', 'Filex'], 
    1: ['File2', 'Filey'], 
    2: [None, 'Filez']
    }, index=[r'C:\users', r'C:\users\paper'])

That looks like this:

>>> df
                    0      1      2
C:\users        File1  File2   None
C:\users\paper  Filex  Filey  Filez

You can create a MultiIndex based on your index/column combinations, then create a new DataFrame using that MultiIndex and the original DataFrame's data, properly reshaped:

index = pd.MultiIndex.from_product([df.index, df.columns])
new_df = pd.DataFrame(df.values.reshape(index.shape), index=index, columns=['filename'])

new_df is:

>>> new_df
                 filename
C:\users       0    File1
               1    File2
               2     None
C:\users\paper 0    Filex
               1    Filey
               2    Filez

Use new_df.dropna() if you don't care about the None value in the filename row.