Recommend a way to do nested field aggregation

[wangweiching (Wei Ching Wang)]

i have the multiple documents query response with multiple dates as followed, I would like to know if we can do aggregation on
those documents for example, I like to aggregate all the predictions elements with same date, the hours values like hours.h1, hours,h2 and hours.h3 and get only a single date prediction element.
...
{
"predictions": [{
"date": "2018-08-10",
"hours": [{
"h1": {
"t": 100
},
"h2": {
"t": 100
}
}]
}]
}