save array in one csv file with headers

Question

I have two lists of tables: old references and new references, I would like to modify this function to save both list in one csv file to get this

old_references= ["POT-94000-FT-42"]
new_references = ["POT-94000-FT-43"]
headers = ["old_references", "new_references"]

I know how to do it in pandas, unfortunately I don't have access to pandas on the computer. thanks for your advice.

def exportCsv(liste):
    date = str(datetime.datetime.now().strftime("%d-%m-%Y %H-%M-%S"))
    csv_file = open(os.path.join(sortie, 'increment_reference_{}_'.format(date) + '.csv'), 'w')
    writer = csv.writer(csv_file)
    writer.writerows([liste])

thanks for your advices

Richard Boyne · Accepted Answer · 2022-04-26 14:05:06Z

1

In csv.writer you should add the header rows at the start. Other than that what you have looks right.

A clean alternative could be csv.DictWriter which is closer to pandas functionality I feel.

dicts = [
    {
     "old_references": old,
     "new_references": new
    }
    for new, old in zip(new_references, old_references)
]
with open('test.csv', 'w') as f:
    writer = DictWriter(f, list[dicts[0]])
    writer.writeheader()
    writer.writerows(dicts)

answered Apr 26, 2022 at 14:05

Richard Boyne

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2 Comments

amaranaitsaidi Over a year ago

When the list of references is empty, have an error : list index out of range. How can i manage this case to export un empty file if the two list are empty ?

Richard Boyne Over a year ago

Here I was using the first index of dicts to avoid having to type out the column headers a second time (since I have them in every dict). You could define the headers separately if you want: writer = DictWriter(f, ["new_references", "old_references"])

roman_repin · Accepted Answer · 2022-04-26 14:09:01Z

It's not entirely clear what kind of liste object you're using. I think it's worth using the writerow method in your case.

writer.writerow(headers)
writer.writerow([old_references[0], new_references[0]])

Also, do not forget that the file must be closed after the end of reading / writing.

csv_file.close()

In order not to prescribe it explicitly every time, it makes sense to use the with context manager.

date = str(datetime.datetime.now().strftime("%d-%m-%Y %H-%M-%S"))
with open(os.path.join(sortie, 'increment_reference_{}_'.format(date) + '.csv'), 'w') as csv_file:
    writer = csv.writer(csv_file)
    writer.writerow(headers)
    writer.writerow([old_references[0], new_references[0]])

In this case, the file will be automatically closed after the end of the context manager.

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