Writing a string with comma in one column of CSV file

[Avi Gross]

Mahmood,
Ask yourself WHY you want to do what you are doing. Are you using the power and features of the language or trying to do it step by step in the way that earlier languages often made you do it?
Yes, there are ways to include commas in fields of a CSV file and they can lead to complications you can completely avoid by NOT using a CSV file. Use something where commas are not a field separator and something else that is not likely to be in your data (or when found is removed or perhaps replaced with something like a space) and can thus be used.
Many files use a TAB or other symbols to delimit data and may be saved with names like a .TSV file or others. Python can trivially read in such files often simply by telling it to read something like a CSV but specifying the field separator is a tab or some other character.
But I have another dumb question. Why are you writing your CSV file by hand and a line at a time? I mean there is nothing wrong with that but many people have programs where they make an object like a DataFrame and manipulate that to have all the data they need and assuming we call the structure df, and they are using the pandas module, they can write the entire thing out like this:

df.to_csv('new_file.sv', sep='\t', index=False)

The pandas package fairly easily allows you to load in all the data you need rom an external source, search in what you have, make changes or additions, and write it out to many kinds of files.
Just a thought. If you like your way, fine, I see another reply suggesting how to hide the commas but that can be a problem if humans read and edit the results in the external file and do not follow through.

-----Original Message-----
From: Mahmood Naderan via Python-list <python-list at python.org>
To: DL Neil via Python-list <python-list at python.org>
Sent: Sat, Jan 15, 2022 3:56 pm
Subject: Writing a string with comma in one column of CSV file

Hi,
I use the following line to write some information to a CSV file which is comma delimited.

f = open(output_file, 'w', newline='')
wr = csv.writer(f)
...
f.write(str(n) + "," + str(key) + "\n" )


Problem is that key is a string which may contain ',' and this causes the final CSV file to have more than 2 columns, while I want to write the whole key as a single column.

I know that wr.writerow([key]) writes the entire key in one column, but I would like to do the same with write(). Any idea to fix that?


Regards,
Mahmood
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