How to create a CSV file if it does not exist and then only append to it Python

Question

I want to know how to create a file if it does not exist in the directory. I want to only append data.

I am getting this error in Python: No such file or directory.

This is my code:

with open (saveAddr+".csv",'a') as allpckts:                            
    writer = csv.DictWriter(allpckts, delimiter=',', fieldnames=header) 
    if pktnum < 2:                                                        
        writer.writerow(dict((fn,fn) for fn in header))                 
        writer.writerow(packet_data)                                    
    else:                                                               
        writer.writerow(packet_data)

Update: My problem was that I wasn't in right directory. So for anyone searching for the most basic syntax to only append to CSV file is:

with open (filename+".csv",'a') as filedata:                            
    writer = csv.DictWriter(filedata, delimiter=',', fieldnames=header)
    writer.writerow(data)

saveAddr is name of the file that I want to create if it does not exist. I my case it is smth. like ED_C0_B0_E0_D2_87 — alphiii, Aug 19 '15 at 06:16
Please show the full error message, not just a snippet of it. It could be that a directory name in the path specified does not exist. — cdarke, Aug 19 '15 at 06:16
May be this information helps you: http://stackoverflow.com/questions/13248020/whats-the-difference-between-r-and-a-when-open-file-in-python — ikoverdyaev, Aug 19 '15 at 06:17
The problem wasnt the this code but it was two lines upper since I wanted to read a file that does not existI just put this code to solve the issue. try: file_read = open(saveAddr+".csv") pktnum = sum(1 for row in file_read) except: pktnum = 0 — alphiii, Aug 19 '15 at 06:27

Anand S Kumar · Accepted Answer · 2015-08-19T06:26:10.540

Most probably you are trying to create a file in a directory which does not exist .

What you want is what 'a' mode does , it creates the file if it does not exist , otherwise it appends to the file . But it would not create the directories , if those directories so not exist , you should create the directories used in saveAddr , before running the program .

If you want a programmatic solution , you can check out os.mkdir , which should create the directory.

itzMEonTV · Answer 2 · 2015-08-19T06:19:27.623

7

with open (saveAddr+".csv",'a') as allpckts:

will create a new file saveAddr+".csv" if not exist, otherwise open it for further appending.Assuming saveAddr is the file name(if path includes in it, check whether path exists.)

If you want to check file exists

os.path.isfile('/path/to/csv')

edited Aug 19 '15 at 06:19

answered Aug 19 '15 at 06:16

itzMEonTV

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score 4 · Answer 3 · answered Apr 14 '18 at 16:23

#check if dir exist if not create it
def check_dir(file_name):
    directory = os.path.dirname(file_name)
    if not os.path.exists(directory):
        os.makedirs(directory)


def save(file_name, records):
    check_dir(file_name)
    csv_file = open(file_name,'w+')
    csvWriter = csv.writer(csv_file,delimiter=',')
    count = 0
    for record in records:
        csvWriter.writerow([record])
        count+=1

    print(count, " record saved to ",file_name)
    return  count    enter code here

directory = os.path.abspath(os.path.join(os.path.curdir))
save(directory+"/data/filename.csv",your_list)

How to create a CSV file if it does not exist and then only append to it Python

3 Answers3