向数据框添加具有更新时间的列

Question

I am new to python and I am playing with pandas libraries. I have a dataframe called COMBO that combines 5 different excel spreadsheets into one master spreadsheet. I want to add a new column at the end showing when and what time I combined the spreadsheets, but I am having a hard time making it to work. I get an error: TypeError: cannot concatenate a non-NDFrame object. Here is what I have tried so far:

import pandas as pd
import datetime


df1= pd.read_excel(r'W:\sheets\sh1.xlsx')
df2= pd.read_excel(r'W:\sheets\sh2.xlsx')
df3= pd.read_excel(r'W:\sheets\sh3.xlsx')
df4= pd.read_excel(r'W:\sheets\sh4.xlsx')
df5= pd.read_excel(r'W:\sheets\sh5.xlsx')
df6= pd.read_excel(r'W:\sheets\sh6.xlsx')


combo = pd.concat([df1,df2,df3,df4,df5,df6])

now = datetime.datetime.now()  #defines NOW
ts = str(now) #converts it into string
timestamp = pd.DataFrame([]) #opens an empty dataframe

for row in combo.iterrows():
    timestamp.append(ts)

master = pd.concat([combo,timestamp],axis=1)

master.to_excel(r'W:\sheets\mastersheet.xlsx',index = False)

Basically, I concatenate the sheets first, then get the date and time, then create a new dataframe that is empty called TIMESTAMP. Then, for every row in the COMBO I append the date and time to the empty dataframe TIMESTAMP (this is so I end up with a column with the same number of rows as the one in the COMBO, all with the same timestamp). At the end, I concatenate TIMESTAMP to the COMBO to generate the MASTER sheet.

I am not sure if the methodology is the correct one, but it is not working. Any help would be appreciated.

thanks

Answer 1

According to your expected output, it may be simpler to just add timestamp column without creating another dataframe

combo = pd.concat(pd.read_excel(r'W:\sheets\sh%d.xlsx' % i) for i in range(1, 7))
combo['timestamp'] = str(datetime.datetime.now())
combo.to_excel(r'W:\sheets\mastersheet.xlsx', index=False)