How to check if an data already present in a CSV file using Python

Question

Good day all,

I am trying to write a python script that picks up IP address(es) from a textfile, check if the IP addresses already present in CSV file, if IP address is already present then do nothing (pass), if the IP is not present in the CSV file then append the IP address in the CSV file.

I can add the IP addresses to the CSV file but I am not able to get my head around with how to check if the IP address is already present in the file.

if os.path.isfile('IP_file.txt'):
    logfile = open('IP_file.txt', 'r')
    csv_file = open('csv_file.csv', 'ab')
    for line in logfile:
        if line in csv_file: # This is not working
            pass
        else:
            csv_file.write(line)
    csv_file.close()
    logfile.close()
else:
    print('No file with filename ' logfile 'created')

I also tried to use the CSV module but no luck. Any help is much appreciated.

Hi Greg, the line from the IP_file.txt will contain the IP addresses... — Bash Noob
– Bash Noob, Commented Nov 26, 2013 at 9:18

peroksid · Accepted Answer · 2013-11-26 08:58:25Z

2

CSV is just a text format. Read it line by line, test every line against your IP. Like

ip="192.168.1.1"
for line in csv_file:
    if ip in line:
        found = True
        break

I am a bit concerned against your cycling over file on the disk. Probably it is better to read files into memories (find all IPs in CSV file first and put in a list) and then check against the list instead of opening and iterating over whole CSV file for every line of IP file.

answered Nov 26, 2013 at 8:58

peroksid

9276 silver badges17 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Bash Noob Over a year ago

Hi @peroksid, thanks for the answer, you are right I might put all the IPs in the text file into a list and then check against the CSV file.

RickyA · Accepted Answer · 2013-11-26 08:58:53Z

1

Keep a list or dict that holds the unique fetched values:

found_address = []
with open('IP_file.txt', 'r') as logfile:
    with open('csv_file.csv', 'ab') as csv_file:
        for line in logfile:
            if not line in found_address:
                csv_file.write(line)
                found_address.append(line)

answered Nov 26, 2013 at 8:58

RickyA

16.1k6 gold badges77 silver badges97 bronze badges

Comments

Chandan · Accepted Answer · 2013-11-26 09:01:58Z

1

You are opening csv_file.csv in append mode ab. And then you are trying to check line in csv_file. In append-mode file-pointer points to the end-of-file.

answered Nov 26, 2013 at 9:01

Chandan

7666 silver badges8 bronze badges

Comments

sheh · Accepted Answer · 2013-11-26 11:05:59Z

1

little crazy functional-style python:

ip_file = set(map(str.strip, open('IP_file.txt').readlines()))

if CSV file is: 192.168.1.1,192.168.1.2,192.168.1.3,...

csv_file = set(map(str.strip, open('csv_file.csv').read().split(',')))
diff_ip = ip_file - csv_file
open('csv_file.csv','a').write(''.join(map(lambda x: ',{}'.format(x), list(diff_ip))))

answered Nov 26, 2013 at 11:05

sheh

1,0331 gold badge9 silver badges31 bronze badges

Collectives™ on Stack Overflow

How to check if an data already present in a CSV file using Python

4 Answers 4

1 Comment

Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

1 Comment

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related