Re: CSV extension status

[Manuel Collado]

El 18/05/2021 a las 14:56, Andrew J. Schorr escribió:
> ...
> I think I understand the conceptual problem, but I feel as if maybe we're
> letting the perfect be the enemy of the good.

Agreed.

> In 99.9% of the cases where I use
> CSV files, I simply want to have read-only access to the fields. Actually, if
> I'm being honest, it's 100%. In other words, I want to be able to say something
> like:
>
> gawk -lcsv '
> NR == 1 {
>         for (i = 1; i <= NF; i++)
>                 m[$i] = i
>         next
> }
>
> $m["age"] > 30 {
>         sum += $m["weight"]
>         n++
> }
>
> END {
>         printf "found %d people over 30 with an average weight of %.3f\n",
>                n, (n? sum/n : 0)
> }'
>
> Can this be done without a library?

Do you mean without an API-based extension? Yes.

> I thought that the possibility of embedded
> newlines meant that we needed a library for this rather than a simple FPAT
> solution. Maybe I'm confused.

A pure gawk library is enough to effectively process CSV data. By using 
my CSVMODE library from http://mcollado.z15.es/xgawk/ your example can 
be coded almost verbatim:

gawk -i csvmode-1 '
NR==1 {next}

csvfield("age") > 30 {
        sum += csvfield("weight")
        n++
}

END {
        printf "found %d people over 30 with an average weight of %.3f\n",
               n, (n? sum/n : 0)
}'

And this code works with fields quoted, unquoted or with embedded 
newlines. This is why I'm unsure if an API-based gawk-csv extension is 
really needed.

How about also hosting pure gawk libraries, like CSVMODE, in the 
gawkextlib site? Arnold suggested this sometime ago.

Regards.

--
Manuel Collado - http://mcollado.z15.es