On Aug 25, 8:49 am, Peter Otten <__pete...@web.de> wrote: > JKPeck wrote: > > On Aug 24, 10:43 pm, John Yeung <gallium.arsen...@gmail.com> wrote: > >> On Aug 24, 5:00 pm, Peter Otten <__pete...@web.de> wrote: > > >> > If I understand you correctly the csv.writer already does > >> > what you want: > > >> > >>> w.writerow([1,None,2]) > >> > 1,,2 > > >> > just sequential commas, but that is the special treatment. > >> > Without it the None value would be converted to a string > >> > and the line would look like this one: > > >> > 1,None,2 > > >> No, I think he means he is getting > > >> >>> w.writerow([1,None,2]) > > >> 1,"",2 > > >> He evidently wants to quote "all" strings, but doesn't want None to be > >> considered a string. > > >> John > > > Exactly so. The requirement of the receiving program, which is out of > > my control, is that all strings be quoted but a None in a numeric > > field result in the ,, output rather than "". Excel quotes strings > > conditionally, which doesn't do what is needed in this case. For > > QUOTE_NONNUMERIC to quote None values makes some sense, but it gets in > > the way of representing missing values in a numeric field. It would > > be nice to have a choice here in the dialects. > > > I thought of replacing the None values with float(nan), since that has > > a numeric type, but unfortunately that results in writing the string > > (unquoted) nan for the value. So the sentinel approach seems to be > > the best I can do. > > How about: > > >>> import csv, sys > >>> class N(int): > > ... def __str__(self): return "" > ...>>> pseudo_none = N() > >>> w = csv.writer(sys.stdout, quoting=csv.QUOTE_NONNUMERIC) > >>> w.writerow([1, "foo", pseudo_none, "bar"]) > > 1,"foo",,"bar" > > Peter
Clever. Thanks, Jon -- http://mail.python.org/mailman/listinfo/python-list