Actually, I should have probably said something like:
({."1 (~.@[,.]/.) {:"1) a,(,.b -.&.:({."1) a),b
But the complexity of that expression hides the basic concept. And, if
your data is already properly conditioned you don't need all that
complexity.
Thanks,
--
Raul
On Tue, Aug 12, 2014 at 7:03 PM, Joe Bogner <[email protected]> wrote:
> Thank you bob and raul. I knew I was overlooking something simple.
> I'll read through that section of J for C again
>
> On Tue, Aug 12, 2014 at 6:54 PM, Raul Miller <[email protected]> wrote:
>> That (using /.) is what I was going to say.
>>
>>
>> S
>>
>> p
>>
>> o
>>
>> i
>>
>> l
>>
>> e
>>
>> r
>>
>>
>>
>> S
>>
>> p
>>
>> a
>>
>> c
>>
>> e
>>
>> .
>>
>> .
>>
>> .
>>
>> ({."1 ]/. {:"1) a,b
>>
>> Thanks,
>>
>> --
>> Raul
>>
>> On Tue, Aug 12, 2014 at 6:36 PM, robert therriault
>> <[email protected]> wrote:
>>> Hi Joe,
>>>
>>> Henry touches on this in JforC: Apply On Subsets: Dyad u/.
>>>
>>> http://www.jsoftware.com/help/jforc/loopless_code_v_partitions.htm#_Toc191734451
>>>
>>> He does a total instead of an append, but I think you'll get the idea.
>>>
>>> Cheers, bob
>>>
>>> On Aug 12, 2014, at 3:19 PM, Joe Bogner <[email protected]> wrote:
>>>
>>>> I've been fiddling with this for 30 minutes and I can't figure it
>>>> out... Maybe it's too late in the day
>>>>
>>>> a=:_2]\'a';1;'b';2;'c';3
>>>> b=:_2]\'c';5;'a';4
>>>>
>>>> what verb will produce this?
>>>>
>>>> ]a,.(4;'';5)
>>>> ┌─┬─┬─┐
>>>> │a│1│4│
>>>> ├─┼─┼─┤
>>>> │b│2│ │
>>>> ├─┼─┼─┤
>>>> │c│3│5│
>>>> └─┴─┴─┘
>>>>
>>>>
>>>> I went down this path:
>>>>
>>>> ] ((0{"1 b)i.(0{"1 a))
>>>> 1 2 0
>>>>
>>>> I figured I could use { and return '' if the index was greater than
>>>> the length (e.g., 2 should be '')
>>>>
>>>> I tried using :: to return '' on index error but I couldn't get that to
>>>> work
>>>>
>>>> NB. not what I wanted
>>>> ] ((0{"1 b)i.(0{"1 a)) ({ :: ('no'"_)) b
>>>> no
>>>>
>>>> Then I tried using ^: to return '' if the length was greater than # b
>>>>
>>>> Then I tried writing a explicit verb using if.
>>>>
>>>> Then I threw in the towel and decided to ask for help since this must
>>>> be a common need
>>>>
>>>> I'm sure I've solved this before but cannot remember how
>>>> ----------------------------------------------------------------------
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>>>
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