Or, there's a general pattern leading in the direction of (the
incredibly useful) linear algebra:
A=:(;:'b c') (0 0;2 2)}3 3$a:
*/"1 a: = A
0 1 0
a: */ .= A
0 1 0
--
Raul
On Wed, Jun 1, 2016 at 8:48 AM, Don Guinn <[email protected]> wrote:
> I'm not sure just how = goes about comparing boxed data, but opening the
> boxes can be avoided by:
> */"1 a:=a
> 0 1 0
>
> On Tue, May 31, 2016 at 11:48 PM, bill lam <[email protected]> wrote:
>
>> step by step example.
>>
>> ] a=. a: (<1)} <"0 i. 3 5
>> +--+--+--+--+--+
>> |0 |1 |2 |3 |4 |
>> +--+--+--+--+--+
>> | | | | | |
>> +--+--+--+--+--+
>> |10|11|12|13|14|
>> +--+--+--+--+--+
>> (0=#) &> a NB.test for empty in each cell
>> 0 0 0 0 0
>> 1 1 1 1 1
>> 0 0 0 0 0
>> *./ (0=#) &> a NB. closed but not what we wanted
>> 0 0 0 0 0
>> *./"1 (0=#) &> a NB. this work with rank operator
>> 0 1 0
>> *./ |: (0=#) &> a NB. transpose also work
>> 0 1 0
>>
>> The key is the adverb &> which open each cell, do something, then
>> assemble again. It also works if you have a more complicated
>> verb instead of tacit (0=#), eg
>>
>> foo=: 3 : 0
>> if. #y do. 1 else. 0 end.
>> )
>>
>> and then proceed with
>> foo &> a
>>
>>
>> Ср, 01 июн 2016, PR PackRat написал(а):
>> > I need to perform a certain action if an entire row in a transposed
>> > table (i.e., originally a column) has empty values, that is, all boxed
>> > data are the equivalent of a: or ''. The result should be a Boolean
>> > value--"true" meaning that the entire row has empty values. (A
>> > typical application would be old stock market data, where all of the
>> > "Open" values might be null or empty.)
>> >
>> > I don't know how to even begin writing such code (without a for/next
>> > loop to separately evaluate each box's value, a very non-J way of
>> > doing it). Please help. Thanks in advance!
>> >
>> >
>> > Harvey
>> > ----------------------------------------------------------------------
>> > For information about J forums see http://www.jsoftware.com/forums.htm
>>
>> --
>> regards,
>> ====================================================
>> GPG key 1024D/4434BAB3 2008-08-24
>> gpg --keyserver subkeys.pgp.net --recv-keys 4434BAB3
>> gpg --keyserver subkeys.pgp.net --armor --export 4434BAB3
>> ----------------------------------------------------------------------
>> 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
