You could key the first column on the values.
(}."1 </. {."1) t
On Jul 25, 2014 7:07 AM, "Joe Bogner" <[email protected]> wrote:
> Given the following data:
>
> t =: ;: ;._2 (0 : 0)
> c1 p1 0.25
> c1 p2 0.35
> c2 p1 0.25
> c2 p2 0.35
> c3 p1 0.25
> c3 p2 0.35
> c3 p3 0.45
> )
>
>
> c1 has two rows (p1 0.25) and (p2 0.35)
> c2 has two rows (p1 0.25) and (p2 0.35)
> c3 has three rows (p1 025), (p2 0.35), (p3 0.45)
>
> How can I identify that c1 and c2 have the same set of values and that c3
> is different?
>
> I'd like to run the algorithm on a 1.6M row table
>
> I created a prototype in javascript using a rough approach, but I haven't
> translated it to J in case there is a better way:
>
> 1. Sort array by column 2 (product)
> 2. Loop through the array and create a hash table of the concatenated
> product/value pair (e.g: p2 0.35) for each customer
> 3. Loop through the hash table and create a list of customers for each
> unique string of product/value pairs
>
> var t = function(){/*
> c1 p1 0.25
> c1 p2 0.35
> c2 p1 0.25
> c2 p2 0.35
> c3 p1 0.25
> c3 p2 0.35
> c3 p3 0.45
> */}.toString().slice(15,-4).split('\n').map(function(x) { return x.split('
> ') })
> t = t.sort(function(x,y) { return x[1]>y[1] })
>
> var cs = t.reduce(function(memo,val) { memo[val[0]] =
> (memo[val[0]]||'')+val[1]+val[2]; return memo;}, {});
>
> //JSON.stringify(cs)
> //"{"c1":"p10.25p20.35","c2":"p10.25p20.35","c3":"p10.25p20.35p30.45"}"
>
> var matches = Object.keys(cs).reduce(function(memo,val) { var key =
> memo[cs[val]] = (memo[cs[val]] || []); key.push(val); return memo;}, {})
>
> JSON.stringify(matches)
>
> "{"p10.25p20.35":["c1","c2"],"p10.25p20.35p30.45":["c3"]}"
>
> How should this problem be approached in J?
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>
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