如何基于特定列将csv文件中的特定行复制到另一个csv文件中？

Question

Let's suppose that this is my data.

 frame.number    frame.len   frame.cap_len   Packets_Type  
  1               100           100           ICMP_tt   
  2                64            64           UDP   
  3               100           100           ICMP_tt   
  4                87            64           ICMP_nn
  5               100           100           ICMP_tt   
  6                87            64           ICMP_nn
  7               100           100           ICMP_tt   
  8                87            64           ICMP_nn
  9                87            64           ICMP_nn

I put my data in a csv file, I want to extract rows where Packets_Type is equal to ICMP_tt

import csv
f = open("file.csv", "rb")
reader = csv.DictReader(f, delimiter=',')
writer = open("newfile.csv",'wb')
writer = csv.writer(writer, delimiter=',')

for row in reader:
    if row['Packets_Type'] == 'ICMP_tt':
        writer.writerow(row)

By executing those lines of code, I found this error:

    writer.writerow(row)
_csv.Error: sequence expected

I would be very grateful if you could help me please.

Answer 1

If you are open to using pandas this could be easily done by:

import pandas as pd

reader = pd.read_csv('file.csv')
writer = reader[reader['Packets_Type']=='ICMP_tt']
writer.to_csv('newfile.csv', index=False)

Answer 2

The issue here is that you are importing your data using csv.DictReader , while at the same time you are exporting the data with csv.writer . csv.writer expects an iterable ( list or tuple ), but the row values are dictionaries. So, the best way to save your data would be to stay consistent and use csv.DictWriter . The following should work:

import csv


with open("file.csv", "rb") as f:
    reader = csv.DictReader(f, delimiter=',')
    with open("newfile.csv", "wb") as f_out:
        writer = csv.DictWriter(f_out, fieldnames=reader.fieldnames, delimiter=",")
        writer.writeheader()
        for row in reader:
            if row['Packets_Type'] == 'ICMP_tt':
                writer.writerow(row)

I hope this proves useful.

Answer 3

import pandas as pd

reader = pd.read_csv('file.csv',sep=',')
writer = reader[reader['Packets_Type']=='ICMP_tt']
writer.to_csv('newfile.csv', index=False)import pandas as pd

adding sep=',' should solve the error