Python - How to add values to first column and appending

Question

So I have a small script that looks pretty much:

for _ in range(3):
    with open('test.csv', 'a', newline='') as csv_file:
        writer = csv.writer(csv_file)
        writer.writerow(["SN", "Name", "Contribution"])
        writer.writerow([1, "Linus Torvalds", "Linux Kernel"])
        writer.writerow([2, "Tim Berners-Lee", "World Wide Web"])
        writer.writerow([3, "Guido van Rossum", "Python Programming"])

sys.exit()

which basically write at this something like:

However what I would like to do is to have something like:

and here basically what I can see for issue is:

If there is no csv called test.csv then we create one and add the Column-1, Column-2, Column-3 only once at top.
If there is already a test.csv then we don't need to add the first column Column-1, Column-2, Column-3but instead just appending into those column that is needed.

And I am not sure how I am able to do that. I would like to know how to do that.

maybe you can use pandas to do this.

Hernan Acosta
– Hernan Acosta

2020-02-25 13:16:28 +00:00
Commented Feb 25, 2020 at 13:16 — Hernan Acosta
– Hernan Acosta, Commented Feb 25, 2020 at 13:16

Mojtaba Kamyabi · Accepted Answer · 2020-02-25 13:44:46Z

1

CSV stands for 'Comma-separated values'. If you can't see your separated values as separated columns you should change your csv viewer delimiter settings (for Excel see here).

also you can put your for loop inside the open block to don't write your headers in every iteration

It is easier to use DictWriter instead of writer like this:

with open('names.csv', 'a', newline='') as csvfile:
    fieldnames = ['A', 'B', 'C']
    writer = csv.DictWriter(csvfile, fieldnames=fieldnames)
    writer.writeheader()
    for _ in range(3):
        writer.writerow({'A': 'SN', 'B': 'NAMES', 'C': 'Contribution'})
        writer.writerow({'A': '1', 'B': 'Linus Torvalds', 'C': 'Linux Kernel'})
        # and so on

edited Feb 25, 2020 at 13:44

answered Feb 25, 2020 at 13:08

Mojtaba Kamyabi

3,6703 gold badges33 silver badges52 bronze badges

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

9 Comments

Thrillofit86 Over a year ago

The problem here is that everything is saved into one columns as I can see through this example. Basically everything is stored at column A

Thrillofit86 Over a year ago

Also if you throw this into a for _ in range(3): it will write the A B C everytime it opens it up aswell.

Mojtaba Kamyabi Over a year ago

what is your software to see .csv files ?

Thrillofit86 Over a year ago

Microsoft Excel - Im not sure if its any different?

Mojtaba Kamyabi Over a year ago

I think you should set your delimiter character in Excel try this: extendoffice.com/documents/excel/…

|

Collectives™ on Stack Overflow

Python - How to add values to first column and appending

1 Answer 1

9 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

9 Comments

Your Answer

Sign up or log in

Post as a guest

Related