trying to get a list of stations with their activities

couchdb_tags.js

/*
here's an activity document:

{
  "name": "a name",
  "stations": ["station1", "station2"]
}

I want a view that will return something like this:

[
{"station1": ["activity_1", "activity_2"]},
{"station2": ["activity_2", "activity_3"]}
]

*/

/*
update: This was simpler than I imagined.

?key="alcove4"

gives this:

{"total_rows":14,"offset":0,"rows":[
{"id":"7f7cbcc33fad2dd105c7295966b478ae","key":"alcove4","value":"7f7cbcc33fad2dd105c7295966b478ae"},
{"id":"8565e47c094f7642c37e36656daeef28","key":"alcove4","value":"8565e47c094f7642c37e36656daeef28"}
]}
*/

map = function(doc) {
  if (doc.type == 'Activity') {
     doc.stations.forEach(function(st) {   
        emit(st, doc._id)
     });
  };
}

reduce = null;