CODEWITHSUNDEEP
pythonpandascsv
maelstromscientist
maelstromscientist

Reputation: 551

Get last row of CSV file and append it onto the end of the same CSV file

I need to retrieve the last row of a CSV file, and append it onto the end to extend it any n number of times. I attempted to do this with Pandas:

df = pd.read_csv('file.csv')
last_row = df.iloc[-1]

last_row.to_csv('file.csv', mode='a', header=False)

However, this appends the last row as a single column into the CSV file. Is there a way to properly append the last row column-wise into the CSV file, preferably using Pandas?

Upvotes: 3

Views: 1210

Answers (2)

maelstromscientist
maelstromscientist

Reputation: 551

Answering my own question:

I have figured out how to maintain the order of columns and append to the end of the existing dataframe. It is worth noting that pd.tail() does not maintain the order of columns. 

df = pd.read_csv('file.csv')

df_fluxes =  df.iloc[[-1] * n] 

df_fluxes.to_csv(run_dir+'em_line_fluxes.csv', mode='a', header=False, index=False)

Upvotes: 0

Umar.H
Umar.H

Reputation: 23099

IIUC, you can use tail and concat to extend your dataframe. 

df = pd.read_csv('file.csv')
last_row = df.tail(1)

last_row = pd.concat([last_row] * n)


last_row.to_csv('file.csv', mode='a', header=False)

Upvotes: 1

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