Creating a waterfall chart from a time-series dataset

so let's say you have a set of metrics that you want to create a time-series on. Maybe your team makes sales forecast on clients that changes over time. You can take a 'snapshot' of that forcast daily thru a scheduled dataflow and an append transformation node. At the end of a certain period your dataset may look like this...
Client Date Forecast 
A   January 3  $1000
B  January 3   $5000
A  March 2     $2000
B March 2     $3000
Code below creates a waterfall chart with a binding to control the grouping trigger.
q = load \"zds_IoTForecast5\";\nstartVal = filter q by {{column(qDateTest_1.selection,[\"cTimeStampText\"]).asEquality('cTimeStampText')}};\nendVal = filter q by {{column(q_SnapDate2_1.selection,[\"cTimeStampText\"]).asEquality('cTimeStampText')}};\nq_A = filter q by {{column(qDateTest_1.selection,[\"cTimeStampText\"]).asEquality('cTimeStampText')}};\nq_B = filter q by {{column(q_SnapDate2_1.selection,[\"cTimeStampText\"]).asEquality('cTimeStampText')}};\nstartVal = group startVal by all;\nstartVal = foreach startVal generate \"Start Value\" as '{{column(static_6.selection,[\"Valu\"]).asObject()}}',number_to_string(sum (startVal.'TotValueUSD'),\"$#,###\") as 'Forecast Delta';\nendVal = group endVal by all;\nresult = group q_A by '{{column(static_6.selection,[\"Valu\"]).asObject()}}' full, q_B by '{{column(static_6.selection,[\"Valu\"]).asObject()}}';\nresult = foreach result generate coalesce(q_A.'{{column(static_6.selection,[\"Valu\"]).asObject()}}', q_B.'{{column(static_6.selection,[\"Valu\"]).asObject()}}') as '{{column(static_6.selection,[\"Valu\"]).asObject()}}',coalesce(sum(q_A.'TotValueUSD'),0) as 'A', coalesce(sum(q_B.'TotValueUSD'),0) as 'B';\nresult = foreach result generate '{{column(static_6.selection,[\"Valu\"]).asObject()}}',number_to_string( B-A,\"$#,###\") as 'Forecast Delta';\nendVal = foreach endVal generate \"Ending Value\" as '{{column(static_6.selection,[\"Valu\"]).asObject()}}',number_to_string(sum (endVal.'TotValueUSD'),\"$#,###\") as 'Forecast Delta';\nresult = order result by '{{column(static_6.selection,[\"Valu\"]).asObject()}}' asc;\nfinal = union startVal,result,endVal;