Opps. My previous post did not address namesTenRows. Using masks instead of
indexing usually simplifies the code.
names =. (header i. <'nameFirst') {"1 data
frequency =. #/.~ names
namesTen =. (10 = frequency) # ~. names
namesTenRows =. (+./ namesTen =/ names) # data
On Tue, Oct 8, 2013 at 4:41 AM, Ganesh Rapolu <[email protected]> wrote:
> names =. (header i. <'nameFirst') {"1 data
> frequency =. #/.~ names
> names =. ~. names
> (10 = frequency) # names
> +-----+-----+-----+-----+-----+------+-----+------+--------+-------+
> |Ruben|Paddy|Cecil|Chico|Edwin|Martin|Kelly|Junior|Jonathan|Duane|
> +-----+-----+-----+-----+-----+------+-----+------+--------+-----+
>
>
> On Tue, Oct 8, 2013 at 4:05 AM, Joe Bogner <[email protected]> wrote:
>
>> I wrote:
>> > Is there a better way to find indices of a subset within a greater list?
>> This is my hacky solution
>>
>> Sorry, please disregard my question. I figured out a cleaner
>> implementation
>> using the table adverb
>>
>> (; > L:0 I. each <"1 (find =/ list)) { list
>>
>> NB. 13 : '(; > L:0 I. each <"1 (x =/ y)) { y'
>> in=:] {~ [: ; [: >L:0 [: I.&.> [: <"1 =/
>>
>> ] find in list
>>
>> ┌─┬─┬─┬─┐
>>
>> │a│a│b│q│
>>
>> └─┴─┴─┴─┘
>>
>>
>> ] (<'a') in ('a';'b')
>>
>> ┌─┐
>>
>> │a│
>>
>> └─┘
>>
>>
>> ] ('a';'b') in ('a';'b';'c';'a')
>>
>> ┌─┬─┬─┐
>>
>> │a│a│b│
>>
>> └─┴─┴─┘
>>
>>
>>
>> idx=:13 : '(; > L:0 I. each <"1 (x =/ y))'
>>
>>
>> Which then lets us do things like the following to merge/join tables
>>
>>
>> (find idx list) { list
>>
>>
>> My previous hack of namesTenRows=.(; L:0 > (3 : '(<y) ([: I. =) names' )
>> each namesTen) { data
>>
>> Becomes: namesTenRows=. (namesTen idx names) { data
>>
>>
>> Also quite a bit faster than the hacky solution
>>
>>
>> ]1e5 * 1e5 (6!:2) '; > L:0 (3 : ''(<y) ([: I. =) list'' ) each find'
>>
>> 0.589178
>>
>>
>> ]1e5 * 1e5 (6!:2) '(find idx list)'
>>
>> 0.224204
>>
>>
>> Fun fun
>>
>>
>> http://www.jsoftware.com/help/dictionary/d420.htm
>> http://www.jsoftware.com/help/learning/18.htm
>>
>> I'd be happy to contribute to a wiki page on slicing/dicing tables. I
>> don't
>> have access to modify the wiki at present.
>>
>>
>> On Tue, Oct 8, 2013 at 9:20 AM, Joe Bogner <[email protected]> wrote:
>>
>> > One more -- matching to a list (joining tables)
>> >
>> > NB. Get the names of everyone from the frequency table with exactly 10
>> > matches
>> >
>> > ]namesTen=. > 0}"1 (10 ([: I. =) (> 1{"1 nameFrequency)) {
>> nameFrequency
>> >
>> > ┌─────┬─────┬─────┬─────┬─────┬──────┬─────┬──────┬────────┬─────┐
>> >
>> > │Ruben│Paddy│Cecil│Chico│Edwin│Martin│Kelly│Junior│Jonathan│Duane│
>> >
>> > └─────┴─────┴─────┴─────┴─────┴──────┴─────┴──────┴────────┴─────┘
>> >
>> >
>> >
>> > namesTenRows=.(; L:0 > (3 : '(<y) ([: I. =) names' ) each namesTen) {
>> data
>> >
>> >
>> > NB. Get the unique names in our subset to validate it matches the above
>> >
>> > ] ~. (colIdx <'nameFirst') {"1 namesTenRows
>> >
>> > ┌─────┬─────┬─────┬─────┬─────┬──────┬─────┬──────┬────────┬─────┐
>> >
>> > │Ruben│Paddy│Cecil│Chico│Edwin│Martin│Kelly│Junior│Jonathan│Duane│
>> >
>> > └─────┴─────┴─────┴─────┴─────┴──────┴─────┴──────┴────────┴─────┘
>> >
>> >
>> >
>> > Is there a better way to find indices of a subset within a greater list?
>> > This is my hacky solution
>> >
>> >
>> > find=.('a';'b';'q')
>> >
>> > list=.('a';'b';'z';'c';'a';'q')
>> >
>> >
>> > ] (; > L:0 (3 : '(<y) ([: I. =) list' ) each find) { list
>> >
>> > ┌─┬─┬─┬─┐
>> >
>> > │a│a│b│q│
>> >
>> > └─┴─┴─┴─┘
>> >
>> >
>> > find xxx list
>> >
>> >
>> >
>> > On Tue, Oct 8, 2013 at 7:14 AM, Ric Sherlock <[email protected]> wrote:
>> >
>> >> A relatively simple adverb like the one below can be useful if you a
>> >> repeatedly trying to access different fields in the table:
>> >>
>> >> NB.*getFields a Returns fields (columns) from y specified in x
>> >>
>> >> NB. EG: 'fieldname' tablehdr getFields table
>> >>
>> >> NB. EG: ('Lastname';'Firstname') hdr getFields dat
>> >>
>> >> NB. y is: table of records
>> >>
>> >> NB. m is: list of boxed field names in y
>> >>
>> >> NB. x is: list of boxed field names to return
>> >>
>> >> getFields=: 1 : 0
>> >>
>> >> :
>> >>
>> >> flds=. boxopen x
>> >>
>> >> idx=. m i. flds
>> >>
>> >> idx {"1 y
>> >>
>> >> )
>> >>
>> >>
>> >> require 'tables/csv'
>> >>
>> >> 'hdr dat'=: split readcsv 'c:/tmp/master.csv'
>> >>
>> >>
>> >> 4{. dat hdr getFields~ 'nameFirst';'birthYear';'weight'
>> >>
>> >>
>> >> ┌──────┬────┬───┐
>> >>
>> >> │Hank │1934│180│
>> >>
>> >> ├──────┼────┼───┤
>> >>
>> >> │Tommie│1939│190│
>> >>
>> >> ├──────┼────┼───┤
>> >>
>> >> │Don │1954│190│
>> >>
>> >> ├──────┼────┼───┤
>> >>
>> >> │Andy │1972│184│
>> >>
>> >> └──────┴────┴───┘
>> >>
>> >>
>> >>
>> >>
>> >> On Tue, Oct 8, 2013 at 11:39 PM, Joe Bogner <[email protected]>
>> wrote:
>> >>
>> >> > Here are a couple other examples:
>> >> >
>> >> > NB. Convert years to a flat list of numbers
>> >> >
>> >> > birthYears=. , L:0 (> ". each ((colIdx <'birthYear') {"1 data))
>> >> >
>> >> >
>> >> > NB. Find players born between 1930 and 1950 named Hank
>> >> >
>> >> > (I. (birthYears > 1930) * (birthYears < 1950) * (names = <'Hank')) {
>> >> data
>> >> >
>> >> >
>> >> > NB. Find players born between 1930 and 1950 named Hank or Tommie
>> >> >
>> >> > (I. (birthYears > 1930) * (birthYears < 1950) * ( (names = <'Hank') +
>> >> > (names = <'Tommie'))) { data
>> >> >
>> >> >
>> >> >
>> >> > NB. http://www.jsoftware.com/jwiki/Essays/DataStructures
>> >> >
>> >> > diff=: -. [
>> >> >
>> >> > intersect=: e. # [
>> >> >
>> >> > union=: ~.@,
>> >> >
>> >> >
>> >> > in=: ] ([: I. =)~ [: < [ NB. 4 : '(<x) ([: I.
>> =)
>> >> y'
>> >> >
>> >> > inT=: 4 : 'x in (colIdx <y) {"1 data'
>> >> >
>> >> >
>> >> > NB. Another style
>> >> >
>> >> > NB. Hank or Tommie - the union of indices
>> >> >
>> >> > (('Hank' inT 'nameFirst') union ('Tommie' inT 'nameFirst')) { data
>> >> >
>> >> >
>> >> > NB. Hank or Tommie AND born in Cuba
>> >> >
>> >> > ((('Hank' inT 'nameFirst') union ('Tommie' inT 'nameFirst'))
>> intersect
>> >> > ('Cuba' inT 'birthCountry')) { data
>> >> >
>> >> >
>> >> >
>> >> > On Tue, Oct 8, 2013 at 3:50 AM, R.E. Boss <[email protected]>
>> wrote:
>> >> >
>> >> > > So 'data' was plural?
>> >> > >
>> >> > >
>> >> > > R.E. Boss
>> >> > >
>> >> > > (Add your info to
>> >> http://www.jsoftware.com/jwiki/Community/Demographics)
>> >> > >
>> >> > >
>> >> > > > -----Original Message-----
>> >> > > > From: [email protected] [mailto:
>> programming-
>> >> > > > [email protected]] On Behalf Of Henry Rich
>> >> > > > Sent: dinsdag 8 oktober 2013 3:52
>> >> > > > To: [email protected]
>> >> > > > Subject: Re: [Jprogramming] Slicing and dicing tables
>> >> > > >
>> >> > > > That is what he meant, but it's a minority opinion.
>> >> > > >
>> >> > > > Henry Rich
>> >> > > >
>> >> > > > On 10/7/2013 8:56 PM, Dan Bron wrote:
>> >> > > > > You mean " 'data' is plural " .
>> >> > > > >
>> >> > > > > -Dan
>> >> > > > >
>> >> > > > > PS: http://en.m.wikipedia.org/wiki/Muphry's_law
>> >> > > > >
>> >> > > > > (Yes, that link is spelled correctly :)
>> >> > > > >
>> >> > > > > Please excuse typos; composed on a handheld device.
>> >> > > > >
>> >> > > > > On Oct 7, 2013, at 8:00 PM, Eldon Eller <[email protected]>
>> >> wrote:
>> >> > > > >
>> >> > > > >> Data are plural.
>> >> > > > >>
>> >> > > > >> On 10/07/2013 02:04 PM, Dan Bron wrote:
>> >> > > > >>> Ganesh Rapolu
>> >> > > > >>>> Because the data is boxed, all comparisons must be boxed.
>> >> > > > >>> This was very well put (one short sentence which both
>> clarifies
>> >> the
>> >> > > > >>> problem and justifies the solution).
>> >> > > > >>>
>> >> > > > >>> -Dan
>> >> > > > >>>
>> >> > > > >>>
>> >> > > > >>>
>> >> > > > >>>
>> >> > --------------------------------------------------------------------
>> >> > > > >>> -- For information about J forums see
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>> >> > > > >>
>> >> > > > >>
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