Re: [basex-talk] Union of maps?

Wow.

Thanks, Rob! That about solves the problem.

On Fri, Jul 17, 2015 at 4:01 AM, Rob Stapper r.stapper@lijbrandt.nl wrote:

Or, retweeked and made for multiple maps (@ Marc thanx for the inspiration)

declare function XQR.map:merge

  ( $mapSet        as map(*)*

  , $mergeFunction as function(*)

  )                as map(*)

  {

    fold-left( $mapSet

             , map {}

             , function( $targetMap

                       , $sourceMap

                       )

                       {

                         map:merge(( $targetMap

                                   , $sourceMap

                                   , for-each( map:keys( $targetMap)[

. = map:keys( $sourceMap)]

                                             , function( $key

                                                       )

                                                       {

                                                         map:entry(

$key

                                                                  ,

$mergeFunction( map:get( $targetMap, $key)

                  , map:get( $sourceMap, $key)

)

                                                                  )

                                                       }

                                             )

                                  ))

                       }

             )

  } ;

Use:

xqr.map:merge( ( map { 'a' : ( 1,2,3,4)

                 , 'b' : ( 4,5,6,7)

                 }

           , map { 'b' : ( 6,7,8,9)

                 , '7' : ( 'x', 'y', 'z')

                 }

           , map { 'b' : ( 9,10,12)

                 , '7' : ( 'x', 'y', 'p')

                 }

           )

         , function( $data1

                   , $data2

                   )

                   {

                     distinct-values(( $data1, $data2))

                   }

         ) ! map:serialize( .)

You’re welcome,

Rob

*Van:* basex-talk-bounces@mailman.uni-konstanz.de [mailto: basex-talk-bounces@mailman.uni-konstanz.de] *Namens *Graydon Saunders *Verzonden:* woensdag 15 juli 2015 20:01 *Aan:* BaseX *Onderwerp:* [basex-talk] Union of maps?

Hi --

In BaseX 8.2.1, I have a bunch of maps; the maps may have some overlap of key values. I would like to merge/find the union of all of these maps while retaining all the values associated with each key in the resulting map-of-all-maps. (Combined map? Any word can be wrong, here! :)

map:merge() doesn't do this; http://docs.basex.org/wiki/Map_Module#map:merge says

"The associated value for each such key is taken from the last map in the input sequence $input that contains an entry with this key." and testing confirms this.

Is there a straightforward way to do this that I'm missing?

Thanks!

Graydon

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