([
{$match: {"sensor": "LTLASTSHOWER"}},
{$project: {
"month": {"$month": "$timestamp"}, "day": {"$dayOfMonth": "$timestamp"}, "value": "$value"}},
{$group: {
_id: {
month: "$month", day: "$day", value: "$value"}}},
{$sort: {
"_id.month": -1, "_id.day": -1}}
])