How can I save files with a progressive number in Python?

Question

I am a Python beginner. I made a script which, after doing what it is supposed to do, creates a file called "report.csv" with some datas I need.

This is how that part of code looks like:

with open('report.csv'), 'x', newline='') as report_file:
    report_writer = csv.writer(report_file)
    report_writer.writerows(array_i_have_to_write_in_csv)

If report.csv does not exists, everything works perfectly. Otherwise, it throws FileExistsError exception.

I'd like to handle it naming files with a progressive number, like "report-001.csv", "report-002.csv", etc. but how can I do that?

Thanks

What do you not know how to do? Add a number to a string? Zero-pad a number? Count up one by one? It's not clear what you specifically need help with. — Random Davis, Jul 15 '22 at 15:09
Maybe this can help you: https://stackoverflow.com/questions/17984809/how-do-i-create-an-incrementing-filename-in-python — Paulo Barbosa, Jul 15 '22 at 15:10
You should create the file first, the open it second. That way you can include logic if the file already exist. — Paul Trimor, Jul 15 '22 at 15:12

score 1 · Accepted Answer · answered Jul 15 '22 at 16:03

you can use f-strings (https://docs.python.org/3/tutorial/inputoutput.html) to name your file:

with open(f"report{i}.csv", "x") as report_file:
    #do sth

now you have to check if report{i}.csv exists in your current working directory.

def incrementForFilename():
    # get current working directory
    cwd = Path.cwd()
    i = 0
    # loop until you find an i, that does not exist in cwd
    while Path(cwd, f"report{i}.csv").is_file():
        i +=1
    return i

you have to run this function before creating your file:

i = incrementForFilename()
with open(f"report{i}.csv", "x") as f:
    f.writelines("something")

Hope this helps.

It definitely did. Thanks. – Dario Costa Aug 23 '22 at 13:48 — Dario Costa, Aug 23 '22 at 13:48

How can I save files with a progressive number in Python?

1 Answers1