[{"seq":1,"cut":[{"script":[{"type":"a","text":"a1"},{"type":"a","text":"a2"},{"type":"b","text":"b1"},{"type":"c","text":"c1"}]},{"script":[{"type":"d","text":"d1"},{"type":"a","text":"a3"},{"type":"c","text":"c2"},{"type":"b","text":"b2"}]}]}]

db.collection.aggregate({$unwind:{path:"$cut",preserveNullAndEmptyArrays:false}},{$unwind:{path:"$cut.script"}},{$group:{"_id":"$seq","a":{$push:{$cond:{if:{$eq:["$cut.script.type","a"]},then:"$cut.script.text",else:"$$REMOVE"}}},"b":{$push:{$cond:{if:{$eq:["$cut.script.type","b"]},then:"$cut.script.text",else:"$$REMOVE"}}},"c":{$push:{$cond:{if:{$eq:["$cut.script.type","c"]},then:"$cut.script.text",else:"$$REMOVE"}}},"d":{$push:{$cond:{if:{$eq:["$cut.script.type","d"]},then:"$cut.script.text",else:"$$REMOVE"}}}}})