FreeMarker sum group - group-by

Question

I'm trying to do the following in Freemarker via NetSuite:
I have the following data on a transaction record i.e. imagine a payment record with a number of lines
Doc No. Amount
1 100
1 100
2 50
3 200
4 50
4 25
5 1000
and I want to be able to output:
Doc No. Total
1 200
2 50
3 200
4 75
5 1000
I think you need to use #list and #assign but not sure??

Answer 1

Here is a snippet that should help out with this question (I hope). This is pulled from one of my PDF templates, where I'm adding up the locationTotal variable.
<#list record.item as item>
<#assign currentLocation=item.custcol_location>
<#if currentLocation=="">
<#assign currentLocation=record.entity>
</#if>
<#if item.itemtype!="Discount" && locationsProcessed?seq_index_of(currentLocation)==-1>
<#assign locationTotal=0>
<#list record.item as item2>
<#assign compareLocation=item2.custcol_location>
<#if compareLocation=="">
<#assign compareLocation=record.entity>
</#if>
<#if compareLocation==currentLocation>
<#assign locationTotal=locationTotal+item2.amount>
</#if>
</#list>
<#assign newList=newList+[{"location":currentLocation,"total":locationTotal}] >
<#assign locationsProcessed=locationsProcessed+[currentLocation] >
</#if>
</#list>