Oh, DUH!
You are right, the implementation is right, I am wrong.
Here's a fixed version of my implementation:
getIf=: 4 :0
if. data=: ".x
n=: #y
idx=: (n{."1 data) i. y
3 < idx getCtCol data
do. x; idx getValCol data end.
)
getVal =: 3 : 0
NB. search for the full key in city_sport (e.g. hat;chicago;baseball
if. #ret=: 'city_sport' getIf y do. ret return. end.
NB. search for city
if. #ret=: 'city' getIf 2 {. y do. ret return. end.
NB. search for sport, meaning we need the 1st and 3rd value from the key
if. #ret=: 'sport' getIf 0 2 { y do. ret return. end.
NB. search for item overall
if. #ret=: 'item' getIf 1 {. y do. ret return. end.
''
)
Thanks!
--
Raul
On Sat, Oct 3, 2015 at 2:33 PM, 'Pascal Jasmin' via Programming
<[email protected]> wrote:
> 3 : 'if. i.0 do. 1 else. 0 end.' 31
> didn't know this was a bug, but something strange for sure.
> From: Raul Miller <[email protected]>
> To: Programming forum <[email protected]>
> Sent: Saturday, October 3, 2015 2:10 PM
> Subject: Re: [Jprogramming] comparing languages - input to show J's strength
> on a lookup/match function
>
> Unfortunately, my first attempt to rewrite your code seems to trigger
> an interpreter bug.
>
> For reference, here's my attempt:
>
> getIf=: 4 :0
> if. data=: ".x
> n=: #y
> idx=: (n{."1 data) i. y
> 3 < idx getCtCol data
> do. x; idx getValCol data end.
> )
>
> getVal =: 3 : 0
> NB. search for the full key in city_sport (e.g. hat;chicago;baseball
> if. ret=: 'city_sport' getIf y do. ret return. end.
> NB. search for city
> if. ret=: 'city' getIf 2 {. y do. ret return. end.
> NB. search for sport, meaning we need the 1st and 3rd value from the key
> if. ret=: 'sport' getIf 0 2 { y do. ret return. end.
> NB. search for item overall
> if. ret=: 'item' getIf 0 { y do. ret return. end.
> ''
> )
>
> What seems to happen is that only the city_sport table gets tested,
> even with empty ret values from that lookup.
>
> This violates the dictionary definition for if.
>
> I guess this means that I'm going to need to go in and find why this
> is happening (unless someone else gets to it before me).
>
> Thanks,
>
> --
> Raul
>
>
> On Sat, Oct 3, 2015 at 8:45 AM, Joe Bogner <[email protected]> wrote:
>> I'm working on an app that needs a function to return a value based upon
>> matching to 4 different sources and returns the most specific match that
>> meets a quality threshold.
>>
>> Here is an example:
>>
>> The last column of every table (e.g. city_sport) indicates the quality
>> threshold and the column before that is the value I'd like if the quality
>> threshold is above 3
>>
>> The logic in words:
>>
>> Search city_sport
>> if not found or quality not sufficient, search city
>> if not found or quality not sufficient search sport
>> if not found or quality not sufficient search item
>>
>> The logic works. I wrote it quickly in J using my natural imperative
>> mindset. I then was able to very quickly translate it into C# (probably
>> demonstrating how imperative my mindset was)
>>
>> J version: https://gist.github.com/joebo/381552e6ad106391e128
>> C# version: https://gist.github.com/joebo/a0ff7eb57ee15ea96c61
>>
>> I'm looking for input on how to rewrite getVal to show improved
>> maintenance, conciseness over the C# version (subjective, I know)
>>
>> Some half-baked thoughts:
>>
>> 1. Instead of using the if., at each step build up all the possible results
>> and find the result in the final step
>>
>> Note: this will be searching a table of 180,000 rows so performance may
>> matter. The current J version doesn't short circuit, but it could fairly
>> easily
>>
>> 2. Some trick with agenda
>>
>>
>> Thanks for any input
>>
>> Code below:
>>
>> city_sport=: ' ' cut every <;._2 (0 : 0)
>> hat chicago baseball 1 5
>> hat chicago football 2 5
>> hat atlanta baseball 3 2
>> hat orlando football 3 3
>> glove orlando baseball 3 3
>> )
>>
>> city=: ' ' cut every <;._2 (0 : 0)
>> hat chicago 1 5
>> hat atlanta 3 2
>> hat orlando 3 3
>> glove orlando 3 3
>> )
>>
>> sport=: ' ' cut every <;._2 (0 : 0)
>> hat baseball 1 5
>> hat football 3 2
>> jersey soccer 3 4
>> )
>>
>> item=: ' ' cut every <;._2 (0 : 0)
>> hat 1 5
>> jersey 2 4
>> )
>>
>> NB. gets the count which is always the last column
>> getCtCol =: ([: ". [: > _1 { {) :: 0:
>>
>> NB. gets the value which is always 2nd to last column
>> getValCol =: ([: ". [: > _2 { {) :: 0:
>>
>> getVal =: 3 : 0
>> NB. search for the full key in city_sport (e.g. hat;chicago;baseball
>> idx =: 0 { (3{."1 city_sport) i. (,: y)
>> ret=:''
>> if. (idx getCtCol city_sport) > 3 do.
>> ret =: 'city_sport';(idx getValCol city_sport)
>> end.
>> NB. search for city
>> idx =: 0 { (2{."1 city) i. (,: 2{."1 y)
>> if. (0 = (#ret)) *. (idx getCtCol city) > 3 do.
>> ret =: 'city';(idx getValCol city)
>> end.
>> NB. search for sport, meaning we need the 1st and 3rd value from the key
>> idx =: 0 { (2{."1 sport) i. (,: 0 2 { y)
>> if. (0 = (#ret)) *. (idx getCtCol sport) > 3 do.
>> ret =: 'sport';(idx getValCol sport)
>> end.
>> NB. search for item overall
>> idx =: 0 { (1{."1 item) i. (,: 0 { y)
>> if. (0 = (#ret)) *. (idx getCtCol item) > 3 do.
>> ret =: 'item';(idx getValCol item)
>> end.
>> ret
>> )
>>
>> smoutput getVal 'hat';'chicago';'baseball'
>> smoutput getVal 'hat';'chicago';'hockey'
>> smoutput getVal 'jersey';'chicago';'soccer'
>> smoutput getVal 'jersey';'chicago';'badmitton'
>>
>> NB. not enough hats in the city/sport match or city match
>> smoutput getVal 'hat';'atlanta';'baseball'
>>
>>
>> Outputs:
>>
>> smoutput getVal 'hat';'chicago';'baseball'
>>
>> ┌──────────┬─┐
>>
>> │city_sport│1│
>>
>> └──────────┴─┘
>>
>> smoutput getVal 'hat';'chicago';'hockey'
>>
>> ┌────┬─┐
>>
>> │city│1│
>>
>> └────┴─┘
>>
>> smoutput getVal 'jersey';'chicago';'soccer'
>>
>> ┌─────┬─┐
>>
>> │sport│3│
>>
>> └─────┴─┘
>>
>> smoutput getVal 'jersey';'chicago';'badmitton'
>>
>> ┌────┬─┐
>>
>> │item│2│
>>
>> └────┴─┘
>> ----------------------------------------------------------------------
>> For information about J forums see http://www.jsoftware.com/forums.htm
>
>
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
>
>
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
----------------------------------------------------------------------
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