[{"user_id":"test@gmail.com","focus_score":[1,2,3,4],"active_score":[3,4,1],"score":10},{"user_id":"abcd@gmail.com","focus_score":[3,4],"active_score":[3,4,1,7,7],"score":3},{"user_id":"test@gmail.com","focus_score":[1,2,3,4,7],"active_score":[3,9,2],"score":7},{"user_id":"abcd@gmail.com","focus_score":[5,7,8],"active_score":[1,3,7],"score":4}]

db.collection.aggregate([{$group:{_id:"$user_id",focus_score:{$push:"$focus_score"},active_score:{$push:"$active_score"},score_sum:{$sum:"$score"}}},{$project:{_id:0,score_sum:1,user_id:"$_id",focus_score:{$reduce:{input:"$focus_score",initialValue:[],in:{$concatArrays:["$$value","$$this"]}}},active_score:{$reduce:{input:"$active_score",initialValue:[],in:{$concatArrays:["$$value","$$this"]}}}}}])