How do I create a sub arrary in awk? - awk

Question

Given a list like:
Dog bone
Cat catnip
Human ipad
Dog collar
Dog collar
Cat collar
Human car
Human laptop
Cat catnip
Human ipad
How can I get results like this, using awk:
Dog bone 1
Dog collar 2
Cat catnip 2
Cat collar 1
Human car 1
Human laptop 1
Human ipad 2
Do I need a sub array? It seems to me like a need an array of "owners" which is populated by arrays of "things."
I'd like to use awk to do this, as this is a subscript of another program in awk, and for now, I'd rather not create a separate program.
By the way, I can already do it using sort and grep -c, and a few other pipes, but I really won't be able to do that on gigantic data files, as it would be too slow. Awk is generally much faster for this kind of thing, I'm told.
Thanks,
Kevin
EDIT: Be aware, that the columns are actually not next to eachother like this, in the real file, they are more like column $8 and $11. I say this because I suppose if they were next to eachother I could incorporate an awk regex ~/Dog\ Collar/ or something. But I won't have that option. -thanks!

Answer 1

awk does not have multi-dimensional arrays, but you can manage by constructing 2D-ish array keys:
awk '{count[$1 " " $2]++} END {for (key in count) print key, count[key]}' | sort
which, from your input, outputs
Cat catnip 2
Cat collar 1
Dog bone 1
Dog collar 2
Human car 1
Human ipad 2
Human laptop 1
Here, I use a space to separate the key values. If your data contains spaces, you can use some other character that does not appear in your input. I typically use array[$a FS $b] when I have a specific field separator, since that's guaranteed not to appear in the field values.

Answer 2

GNU Awk has some support for multi-dimensional arrays, but it's really just cleverly concatenating keys to form a sort of compound key.
I'd recommend learning Perl, which will be fairly familiar to you if you like awk, but Perl supports true Lists of Lists. In general, Perl will take you much further than awk.
Re your comment:
I'm not trying to be superior. I understand you asked how to accomplish a task with a specific tool, awk. I did give a link to the documentation for simulating multi-dimensional arrays in awk. But awk doesn't do that task well, and it was effectively replaced by Perl nearly 20 years ago.
If you ask how to cross a lake on a bicycle, and I tell you it'll be easier in a boat, I don't think that's unreasonable. If I tell you it'll be easier to first build a bridge, or first invent a Star Trek transporter, then that would be unreasonable.