从CSV解析列，并将文本文件中的值替换为新值

Question

I have one CSV file, and I want to extract the first column of it. My CSV file is like this:

Device ID;SysName;Entry address(es);IPv4 address;Platform;Interface;Port ID (outgoing port);Holdtime
PE1-PCS-RANCAGUA;;;192.168.203.153;cisco CISCO7606 Capabilities  Router Switch IGMP;TenGigE0/5/0/1;TenGigabitEthernet3/3;128 sec
P2-CORE-VALPO.cisco.com;P2-CORE-VALPO.cisco.com;;200.72.146.220;cisco CRS Capabilities  Router;TenGigE0/5/0/0;TenGigE0/5/0/4;128 sec
PE2-CONCE;;;172.31.232.42;Cisco 7204VXR Capabilities  Router;GigabitEthernet0/0/0/14;GigabitEthernet0/3;153 sec
P1-CORE-CRS-CNT.entel.cl;P1-CORE-CRS-CNT.entel.cl;;200.72.146.49;cisco CRS Capabilities  Router;TenGigE0/5/0/0;TenGigE0/1/0/6;164 sec

For that purpose I use the following code that I saw here:

import csv

makes = []
with open('csvoutput/topologia.csv', 'rb') as f:
    reader = csv.reader(f)
#    next(reader) # Ignore first row

    for row in reader:
        makes.append(row[0])

print makes

Then I want to replace into a textfile a particular value for each one of the values of the first column and save it as a new file.

Original textfile:

    PLANNED.IMPACTO_ID = IMPACTO.ID   AND 
    PLANNED.ESTADOS_ID = ESTADOS_PLANNED.ID   AND 
    TP_CLASIFICACION.ID = TP_DATA.ID_TP_CLASIFICACION   AND 
    TP_DATA.PLANNED_ID = PLANNED.ID AND 
    PLANNED.FECHA_FIN >= CURDATE() - INTERVAL 1 DAY AND 
    PLANNED.DESCRIPCION LIKE '%P1-CORE-CHILLAN%’;

Expected output:

    PLANNED.IMPACTO_ID = IMPACTO.ID   AND 
    PLANNED.ESTADOS_ID = ESTADOS_PLANNED.ID   AND 
    TP_CLASIFICACION.ID = TP_DATA.ID_TP_CLASIFICACION   AND 
    TP_DATA.PLANNED_ID = PLANNED.ID AND 
    PLANNED.FECHA_FIN >= CURDATE() - INTERVAL 1 DAY AND 
    PLANNED.DESCRIPCION LIKE 'FIRST_COLUMN_VALUE’;

And so on for every value in the first column, and save it as a separate file.

How can I do this? Thank you very much for your help.

Answer 1

You could just read the file, apply changes, and write the file back again. There is no efficient way to edit a file (inserting characters is not efficiently possible), you can only rewrite it.

If your file is going to be big, you should not keep the whole table in memory.

import csv

makes = []
with open('csvoutput/topologia.csv', 'rb') as f:
  reader = csv.reader(f)
  for row in reader:
      makes.append(row)

# Apply changes in makes

with open('csvoutput/topologia.csv', 'wb') as f:
  writer = csv.writer(f)
  writer.writerows(makes);