How to write a csv with a comma as the decimal separator?

Question

I am trying to create a european-formatted csv in python. I already set the separator to a semicolon

writer = csv.writer(response, delimiter=';', quoting=csv.QUOTE_ALL)

However, this still uses dot . as the decimal separator. What's the correct way to make it use a comma, as is correct for my locale? I can't seem to find any way to set it in the docs. (I am using, and would prefer to stick to, the built-in csv module)

Solution

A little bit hacky way, but it's the best I can think of: convert floats to strings and replace . with ,:

def localize_floats(row):
    return [
        str(el).replace('.', ',') if isinstance(el, float) else el 
        for el in row
    ]

for row in rows:
    writer.writerow(localize_floats(row))

If you want better localization handling, I suggest you convert all numbers using babel.numbers package.

Comments

[martineau]

@maniexx: Yes, the other question is about reading and yours is about writing. However that is a minor difference, since the solution in either case is to replace the decimal mark character with something else, '.' with ',' or vice-versa in the duplicate. The answers to the other question are slightly better, IMO, because they also deal with potential issues when dealing with large numbers with a mixture of the two character in them, as well as describing code that does things in a locale-aware way.

[Basj]

As stated by OP, this got marked as a duplicate, but the linked question concerns reading and not writing.

[Michel de Ruiter]

Although the solution might be similar, the question is not a duplicate!

[Ali SAID OMAR]

What the about the decimal separator from the data source ?

[maniexx]

Won't they be encoded as strings in the csv? IE quoted and interpreted as strings by other software?

[skovorodkin]

They won't be quoted as you set ; as delimiter.

[skovorodkin]

I don't know how other software will handle such format though. IMO it's easier to output numbers as is and then localize them when you really need that (e.g. in UI).

[maniexx]

Yeah, but the csv is going to be read in excel and such. So that's sadly not an option. And an XLS(x) or some other format which is actually a format is not allowed either.

[skovorodkin]

Got it. Then just replace dots with commas or use Babel's format_number function. It'll work.

[maniexx]

I tested your answer, it works for me. Thanks a lot, and I'll be sure to checkout babel if it turns out I need localization somewhere else. (Right now django handles it for me in most places, so I don't want to add it just for this one minor functionality)