Hi Marc --

That looks very helpful.

(Just as soon as I get over feeling like a cabbage for forgetting about fold-left()!)

thanks! Graydon

On Wed, Jul 15, 2015 at 3:51 PM, Marc van Grootel < marc.van.grootel@gmail.com> wrote:

Hi Graydon, have a look here https://github.com/xokomola/fold/blob/dbb79c60a7356e32a0994e581ad4f7f5377ddc...

hope it helps

--Marc

On 15 jul. 2015, at 20:01, Graydon Saunders graydonish@gmail.com wrote:

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

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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Thank you!

Are these easy enough that a map:union() function operating on a sequence of maps isn't something to ask for in the next spec iteration?

-- Graydon

On Fri, Jul 17, 2015 at 4:18 AM, Christian Grün christian.gruen@gmail.com wrote:

Hi Graydon,

here is one more aproach for (it's not so flexible as the functional approach, though):

declare function local:merge($maps as map(*)*) as map(*) { map:merge( for $key in distinct-values($maps ! map:keys(.)) return map { $key: ($maps ! .($key)) } ) };

local:merge(( map { 'A': 1, 'B': 2 }, map { 'A': 3, 'C': 4 } ))

Cheers, Christian

On Wed, Jul 15, 2015 at 8:01 PM, Graydon Saunders graydonish@gmail.com wrote:

...

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

talk@x-query.com says "too late for 3.1 (for a two-liner)" which is fair enough.

The Michael Kay version of the 2-liner looks like:

return map:merge( for $k in distinct-values($maps!map:keys(.)) return map:entry($k, $maps?($k)) )

Your version looks like: map:merge( for $key in distinct-values($maps ! map:keys(.)) return map { $key: ($maps ! .($key)) } )

I feel like I ought to update the docs with one or both but I don't understand the syntax in the return statement of either!

Any chance of getting either or both expanded for the easily-bewildered?

On Sat, Jul 18, 2015 at 8:19 AM, Christian Grün christian.gruen@gmail.com wrote:

...

Are these easy enough that a map:union() function operating on a

sequence of

...

maps isn't something to ask for in the next spec iteration?

Maybe yes. Feel free to propose it on the W3 issue tracker [1]. The talk@x-query.com mailing list may be another place to discuss this.

Best, Christian

[1] https://www.w3.org/Bugs/Public/describecomponents.cgi?product=XPath%20%2F%20...

...

On Fri, Jul 17, 2015 at 4:18 AM, Christian Grün <

christian.gruen@gmail.com>

...

wrote:

...

Hi Graydon,

here is one more aproach for (it's not so flexible as the functional approach, though):

declare function local:merge($maps as map(*)*) as map(*) { map:merge( for $key in distinct-values($maps ! map:keys(.)) return map { $key: ($maps ! .($key)) } ) };

local:merge(( map { 'A': 1, 'B': 2 }, map { 'A': 3, 'C': 4 } ))

Cheers, Christian

On Wed, Jul 15, 2015 at 8:01 PM, Graydon Saunders <graydonish@gmail.com

...

wrote:

...

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