[Jprogramming] indices

[Nollaig MacKenzie]

On 2007.09.03 16:02:01, you,
 the extraordinary adam dunne, emitted:

> Date: Mon, 3 Sep 2007 16:02:01 +0530
> From: "adam dunne" <adamdun at gmail.com>
> To: "Programming forum" <programming at jsoftware.com>
> Subject: [Jprogramming] indices
> 
> NB.suppose i have a list:
>    z=.5 5 2 20 20 20 60 60 2 2
>    =z
> 1 1 0 0 0 0 0 0 0 0
> 0 0 1 0 0 0 0 0 1 1
> 0 0 0 1 1 1 0 0 0 0
> 0 0 0 0 0 0 1 1 0 0
>    NB.how can i generate a list of what will be indices:
>    NB.  0 0 1 2 2 2 3 3 4 4
>    NB.from original list

If one has the nub, say nz, and the selfclassify, say scz, of a list z,

	z -: (,@:I.@|: scz){nz

e.g.:

z=: (?10#3){'abc'
nz=: ~. z
scz=: =z

   z;nz;scz
+----------+---+-------------------+
|bbcbcbaaac|bca|1 1 0 1 0 1 0 0 0 0|
|          |   |0 0 1 0 1 0 0 0 0 1|
|          |   |0 0 0 0 0 0 1 1 1 0|
+----------+---+-------------------+
   (,@:I.@|: scz){nz
bbcbcbaaac

-- 
Nollaig MacKenzie
http://www.yorku.ca/nollaig