M101J-W3

aggregate.js

var min_homeworks = db.students.aggregate([{"$unwind": "$scores"}, {"$match": {"scores.type": "homework"}}, {"$group": {"_id":"$_id", min_score: {"$min":"$scores.score"}}}]);
while (min_homeworks.hasNext()) { 
  var doc = min_homeworks.next(); 
  db.students.update({"_id": doc["_id"]}, {"$pull": {"scores": {"type": "homework", "score": doc["min_score"]}}}); 
}