You've got the arguments to i. backwards--the list to be searched is the
left argument and the element to find is on the right. Assuming that hdr
contains boxes, you also want the element to search for to be boxed.
Then you would have
hdr i. <'NameGiven'
to find the name column.
Another note is that for selecting column n from a table, (n {"1 t),
which selects the nth element from each row of the table, is more
idiomatic and generally easier to use than your ((<a:; n) { t).
Marshall
On Mon, Oct 07, 2013 at 12:59:13PM -0700, Dan Farmer wrote:
> Hello all,
>
> As I have been trying to improve my J skills I've been trying to
> incorporate it into my daily work, but I keep hitting a wall with my
> ability to dig in to "tables" (i.e., read in a CSV and then explore
> the data).
>
> I've seen Dan Bron mention perhaps putting together a wiki page about
> this, but I thought maybe I could start the ball rolling here and
> maybe we could put something together... together. I'm using the
> baseball archive database as sample data since anyone can get at it
> (2012 CSV data, it's an 8MB zip and I'm looking at Master.csv):
> http://www.seanlahman.com/baseball-archive/statistics/
>
> I run off the rails pretty quickly. If I could get this type of stuff
> done then I could double my usage of J day to day which would be a big
> help in learning more. Here's my poor attempt:
>
> load 'tables/csv'
>
> t=. readcsv '/home/dan/Downloads/Master.csv'
>
>
> NB. Let's see how many players are named Joe?
>
> NB. Hmm... first I need to know what the headers are
>
>
> hdr=.0{t
>
>
> NB. Ok. I want rows where nameGiven
>
> NB. is Joe (I won't worry about nicknames for
>
> NB. example purposes).
>
> NB. I can get a column like this:
>
> (<a:; 1) { t
>
>
> NB. So if I can figure out the index of
>
> NB. nameGiven in hdr then I can select that
>
> NB. column, then do the same thing to get the "Joe's"
>
>
> NB. Index of?
>
> 'nameGiven' i. hdr
>
>
> NB. Nope, doesn't work. Looks like it treats
>
> NB. each letter as an item (I guess this is because
>
> NB. the shape of hdr is not e.g., rows x columns anymore)
>
>
> NB. I could of course try the inverted table thing:
>
> ifa =: <@(>"1)@|:
>
> it=. ifa t
>
>
> NB. Well, now my header row is split among the columns,
>
> NB. Ok let's just count with our fingers and try:
>
> 'Joe' i. 16 { it NB. 3
>
>
> NB. ok. I'm confused enough to stop now.
>
>
> Anyway, any help would be appreciated.
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