Sorry, I hit send too early. My complete answer is:
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
c4 p1 0.25
)
]key=. (}."1</.{."1) t
(<"1 t) ,.~ (;key) ,. (<"1|:e.key)
Rows with the same signature i.e., 'raise in' (2nd column) share the sam
values. You'll have to try it on the 1.6m rows to test its speed. I'm
curious.
On Fri, Jul 25, 2014 at 7:19 AM, Thomas Costigliola <[email protected]>
wrote:
> 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?
>> ----------------------------------------------------------------------
>> For information about J forums see http://www.jsoftware.com/forums.htm
>>
>
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