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| From | Neil Cerutti <neilc@norwich.edu> |
| Newsgroups | comp.lang.python |
| Subject | Re: How to: Coordinate DictReader and Reader for CSV |
| Date | 21 Nov 2011 15:43:25 GMT |
| Organization | Norwich University |
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On 2011-11-21, Neil Cerutti <neilc@norwich.edu> wrote:
> On 2011-11-21, ray <ray@aarden.us> wrote:
>> Is there a way to capture the keys outside of the for loop so
>> when the for loop is entered, only data is extracted?
>
> I have sometimes done the following type of thing, since
> DictReader doesn't offer an attribute providing the field names.
> This is Python 3.3.2 code, so revise boilerplate if necessary.
>
> # Open once as a csv.reader instance to get the field names, in
> # order.
> with open(in_file_name, newline='') as in_file:
> reader = csv.reader(in_file)
> fields = next(reader)
Equal to reader.next() in 2.x Python, I believe.
> # Open it again as a csv.DictReader instance to do actual work,
> # writing revised lines to the output file as I go.
> with open(in_file_name, newline=') as in_file:
> with open(out_file_name, "w", newline='') as out_file:
> reader = csv.DictReader(in_file)
> writer = csv.DictWriter(out_file, fieldnames=fields)
> # Write header line
> writer.writerow({f: f for n in fields})
Oops! {f: f for f in fields}. Sorry about that.
> for record in reader:
> # Change a few fields
> # [...]
> writer.writerow(record)
--
Neil Cerutti
"This room is an illusion and is a trap devisut by Satan. Go
ahead and dauntlessly! Make rapid progres!"
--Ghosts 'n Goblins
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How to: Coordinate DictReader and Reader for CSV ray <ray@aarden.us> - 2011-11-21 05:18 -0800
Re: How to: Coordinate DictReader and Reader for CSV Neil Cerutti <neilc@norwich.edu> - 2011-11-21 13:59 +0000
Re: How to: Coordinate DictReader and Reader for CSV ray <ray@aarden.us> - 2011-11-21 07:16 -0800
Re: How to: Coordinate DictReader and Reader for CSV Neil Cerutti <neilc@norwich.edu> - 2011-11-21 15:41 +0000
Re: How to: Coordinate DictReader and Reader for CSV Neil Cerutti <neilc@norwich.edu> - 2011-11-21 15:43 +0000
Re: How to: Coordinate DictReader and Reader for CSV Tim Chase <python.list@tim.thechases.com> - 2011-11-21 12:36 -0600
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