Create a helper function to wrap a list of Aggregations and hide JPY from users

[jmao-denver]

in deephaven/init_.py, add

JArrayList = jpy.get_type("java.util.ArrayList")
def combo_agg(aggs:List[Aggregation]):
   j_agg_list = JArrayList()
   for agg in aggs:
       j_agg_list.add(agg)
   return j_agg_list

to use:

aggs = combo_agg([Aggregation.Avg(...), Aggregation.Sum(...)])
t.aggBy(aggs, by)

[jmao-denver]

a working example:

from deephaven.TableTools import newTable, stringCol, intCol, doubleCol
from deephaven import Aggregation, combo_agg
Arrays = jpy.get_type("java.util.Arrays")

source = newTable(
    stringCol("X", "A", "B", "A", "C", "B", "A", "B", "B", None),
    stringCol("Y", "M", "N", None, "N", "P", "M", None, "P", "M"),
    intCol("Number", 55, 76, 20, 130, 230, 50, 73, 137, 214),
)

aggs =  combo_agg([Aggregation.AggAvg("Number")])

result = source.aggBy(aggs, "X")