Merge scala map and update common key based on condition - scala

Question

I wrote following code to merge map and update common keys. Is there any better way to write this
case class Test(index: Int, min: Int, max: Int, aggMin: Int, aggMax: Int)
def mergeMaps(oldMap: Map[Int, Test], newMap: Map[Int, Test]): Map[Int, Test] = {
val intersect: Map[Int, Test] = oldMap.keySet.intersect(newMap.keySet)
.map(indexKey => indexKey -> (Test(newMap(indexKey).index, newMap(indexKey).min, newMap(indexKey).max,
oldMap(indexKey).aggMin.min(newMap(indexKey).aggMin), oldMap(indexKey).aggMax.max(newMap(indexKey).aggMax)))).toMap
val merge = (oldMap ++ newMap ++ intersect)
merge
}
Here is my test case
it("test my case"){
val oldMap = Map(10 -> Test(10, 1, 2, 1, 2), 25 -> Test(25, 3, 4, 3, 4), 46 -> Test(46, 3, 4, 3, 4), 26 -> Test(26, 1, 2, 1, 2))
val newMap = Map(32 -> Test(32, 5, 6, 5, 6), 26 -> Test(26, 5, 6, 5, 6))
val result = mergeMaps(oldMap, newMap)
//Total elements count should be map 1 elements + map 2 elements
assert(result.size == 5)
//Common key element aggMin and aggMax should be updated, keep min aggMin and max aggMax from 2 common key elements and keep min and max of second map key
assert(result.get(26).get.aggMin == 1)//min aggMin -> min(1,5)
assert(result.get(26).get.aggMax == 6)//max aggMax -> max(2,6)
assert(result.get(26).get.min == 5)// 5 from second map
assert(result.get(26).get.max == 6)//6 from second map
}

Answer 1

Here's a slightly different take on a solution.
def mergeMaps(oldMap :Map[Int,Test], newMap :Map[Int,Test]) :Map[Int,Test] =
(oldMap.values ++ newMap.values)
.groupBy(_.index)
.map{ case (k,v) =>
k -> v.reduceLeft((a,b) =>
Test(k, b.min, b.max, a.aggMin min b.aggMin, a.aggMax max b.aggMax))
}
I could have followed the groupBy() with mapValues() instead of map() but that doesn't result in a pure Map.

Answer 2

Another version to do the same task.
def mergeMaps(oldMap: Map[Int, Test], newMap: Map[Int, Test]): Map[Int, Test] = {
(newMap ++ oldMap).map(key => {
val _newMapData = newMap.get(key._1)
if (_newMapData.isDefined) {
val _newMapDataValue = _newMapData.get
val oldMapValue = key._2
val result = Test(_newMapDataValue.index, _newMapDataValue.min, _newMapDataValue.max,
oldMapValue.aggMin.min(_newMapDataValue.aggMin), oldMapValue.aggMax.max(_newMapDataValue.aggMax))
(key._1 -> result)
} else (key._1 -> key._2)
})
}