From: Kaldrenon <kaldrenon@...>
Date: 2007-08-17T00:40:00+09:00
Subject: Re: grep a csv?

On Aug 16, 3:04 am, Alex Young <a...@blackkettle.org> wrote:
> There's a problem with using File.readlines that I don't think anyone's
> mentioned yet.  I don't know if it's relevant to your dataset, but CSV
> fields are allowed to contain newlines if the field is quoted.  For
> example, this single CSV row will break your process:
>
> 1,2,"foo
> Blah1",bar
>
> The only way around that is to actually parse the file, so unless you
> *know* that's not going to be a problem, I'd still suggest FasterCSV...

I guess the following is slightly OT, since the OP is talking about
grabbing whole lines, but it's a CSV-relevant question:

Another danger with not using CSV packages (as I've learned from my
present non-use of said packages) is that quoted elements in a row can
contain commas. I'm a fairly inexperienced programmer, and not just in
Ruby, and I haven't yet figured out an elegant way to break this down.

For example:

foo,bar,"foo,bar" is a three-column row in a CSV file, but using
split(/,/) on it will, of course, return ["foo","bar","\"foo","bar
\""], an array of size four. What's an efficient, elegant way of
gathering quoted columns? I'm sure FasterCSV is capable of dealing
with such things, but it's something I'd like to actually learn,
rather than finding a way around it.