Writing strings to CSV causing issue where the string in CSV is separated by commas (Python)

Question

I am facing an issue that I was not able to resolve so far. I need to save a list of strings into the CSV file. I am able to do it however the strings from each element of the list are separated by commas. Why is that and what do I need to do to resolve this issue? Sorry for maybe simple question I am new to programming. I know it has to be somehow related to the string properties where each number is similar to an item in the list and is indexed however I was not able to find the cause of this behavior and how to resolve it.

Here is the code:

duplicity = ['8110278643', '8110278830', '8110283186']

with open("duplicty.csv", "w", newline="") as duplicity_csv:
    output_writer = csv.writer(duplicity_csv)
    header = ["Number"]
    output_writer.writerow(header)
    for item in duplicity:
        output_writer.writerow(item)

The output of this code in CSV is following:

Number
8,1,1,0,2,7,8,6,4,3
8,1,1,0,2,7,8,8,3,0
8,1,1,0,2,8,3,1,8,6

The expected output should be:

Thanks a lot for your replies!

Daniel Fainberg · Accepted Answer · 2022-08-24 11:33:25Z

2

The writerow method takes an iterable of strings. Each item in your list is in fact an iterable -- namely a string. Each element from that iterable (in your case each letter in the string) is taken as its own element in a sperate column.

You could just do this instead:

...
    for item in duplicity:
        output_writer.writerow([item])

edited Aug 24, 2022 at 11:33

answered Aug 24, 2022 at 11:28

Daniel Fainberg

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2 Comments

Samurajx Over a year ago

perfect thanks a lot it's working! so if i put the item of the list into a variable and use [], the whole payload of the variable is considered as 1 element?

Daniel Fainberg Over a year ago

@Samurajx Yes, in your case each item is a string. So if you enclose it in [], you now have a list (an iterable) of strings of length 1. The item string is then considered one element. I would appreciate if you marked the answer as accepted, if it helped you.

funnydman · Accepted Answer · 2022-08-24 11:30:38Z

1

Use writerows, for example:

duplicity = ['8110278643', '8110278830', '8110283186']

with open("duplicty.csv", "w", newline="") as duplicity_csv:
    output_writer = csv.writer(duplicity_csv)
    header = ["Number"]
    output_writer.writerows([row] for row in header + duplicity)

answered Aug 24, 2022 at 11:30

funnydman

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Comments

furas · Accepted Answer · 2022-08-24 11:32:29Z

1

writerow() needs list with items (even when you have single item in row) but you use single string and it treads it as list of chars

You need

output_writer.writerow( [item] )

edited Aug 24, 2022 at 11:32

answered Aug 24, 2022 at 11:28

furas

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2 Comments

Daniel Fainberg Over a year ago

No, it doesn't need a list. Any iterable works. Also char is not a thing in Python. The single string is an iterable of strings.

furas Over a year ago

@DaniilFajnberg frankly, it is not important details to solve problem. And list of chars can be more readable for beginners.

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