CODEWITHSUNDEEP
pythoncsv
Sarjan
Sarjan

Reputation: 51

How to copy rows from one CSV to another CSV file using Python

I am trying to copy rows from one CSV to another, and also to remove rows after being copied from the first file.

Please see the code, it is working for only copying specific rows from one CSV file to another, but it is not removing the rows from file 1.

import csv
import os

File1 = 'in.csv'
File2 = 'out.csv'

with open(File1, "r") as r, open(File2, "a") as w: 
     reader = csv.reader(r, lineterminator = "\n")
     writer = csv.writer(w, lineterminator = "\n")

     for counter,row in enumerate(reader):
         if counter<0: continue
         if counter>50:break
         writer.writerow(row)

with open(File1, "w") as r: 
     reader = csv.writer(r, lineterminator = "\n")

     for counter,row in enumerate(reader):
         if counter<0: continue
         if counter>50:break
         reader.writerow(row)

Please let me know how this would work after coping the rows to the File 2 and then remove those rows from File 1.

Here is the error:

for counter,row in enumerate(reader):
TypeError: '_csv.writer' object is not iterable

Upvotes: 2

Views: 17459

Answers (1)

Martin Evans
Martin Evans

Reputation: 46759

You appear to be trying to move the first 50 rows from one file and append them to another. This needs to be done in a few steps:

  1. Read each of the 50 rows from in.csv and append each one to out.csv.

  2. Write the remaining rows from in.csv to a temporary file.

  3. Delete the original in.csv file and rename the temporary file to be in.csv.

For example:

import itertools
import csv
import os

file_in = 'in.csv'
file_out = 'out.csv'
file_temp = '_temp.csv'

with open(file_in, "r", newline='') as f_input, \
     open(file_out, "a", newline='') as f_output, \
     open(file_temp, "w", newline='') as f_temp:
    
    csv_input = csv.reader(f_input)

    # Append first 50 rows to file_out
    csv.writer(f_output).writerows(itertools.islice(csv_input, 0, 50))

    # Write the remaining rows from file_in to file_temp
    csv.writer(f_temp).writerows(csv_input)

# Rename f_temp to file_in, first remove existing file_in then rename temp file
os.remove(file_in)
os.rename(file_temp, file_in)

This assumes you have a standard comma delimited file and that you are using Python 3.x.

Upvotes: 2

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