CSV Module questions.

Dave Cole djc at object-craft.com.au
Mon Sep 8 03:13:26 CEST 2003

> I'm trying to understand how to use the "csv" module.  I assume this
> means "comma seperated values" in files.  I quote from the docs...
> http://python.org/doc/current/lib/csv-fmt-params.html "When creating
> reader or writer objects, the programmer can specify a string or a
> subclass of the Dialect class as the dialect parameter"
> Ok, that's fine and dandy, but how do I specify it when I want to
> create a "writer" to write a simple dictionary to a file, and
> specify how it's to be written?
> Example (from the docs):
> # Just some stupid dictionary with key same as value.
> someiterable = {'john d': 'john d', 'fred': 'fred'}
> # make the writer.
> writer = csv.writer(file("some.csv", "w"))
> for row in someiterable:
>     writer.writerow(row)
> Ok,  so this made the file,  but the file contents are thus...
> $ less some.csv
> j,o,h,n, ,d
> f,r,e,d
> which is NOT what I want.  Obviously I have to probably make a
> "Dialect" or something like that.  But how do I do that?  Obviously,
> since Python severely lacks acceptable example code....  why didn't
> they just put in a few examples of how to do this?  I certainly
> cannot figure this out.
> Here is what I want...
> "john d", "john d"
> "fred", "fred"
> How to I write to a file in this way?    Is is possible?

When you write a "row" the writer expects the "row" to be a sequence.
Passing a string as the "row" the writer causes the string to be
handled as a row sequence thereby producing a row of single

Try this:

>>> import sys, csv
>>> w = csv.writer(sys.stdout)
>>> someiterable = {'john d': 'john d', 'fred': 'fred'}
>>> w.writerows(someiterable.iteritems())
john d,john d

- Dave


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