[SalesForce] assign Aggregate SOQL Result directly to variable

This is untested so you may need to have play, however this should return a List of the RevenueWrapper classes which contains the 4 columns you are looking to use in your VF page:

public class RevenueController{

Map<String, RevenueWrapper> ResultList = new Map<String, RevenueWrapper>(); 

public RevenueController(){
    List<AggregateResult> result =  [
    SELECT FISCAL_YEAR(Date__c) Date, Type__c, sum(Amount__c) Amount
    FROM Revenue__c
    GROUP BY FISCAL_YEAR(Date__c), Type__c];

    for(AggregateResult ar : result){

        RevenueWrapper RW = new RevenueWrapper();

        //If the RevenueWrapper already exists grab it from the Map
        if(ResultList.containsKey(String.valueOf(ar.get('Date')))){
            RW = ResultList.get(String.valueOf(ar.get('Date')));
        }

        //Set the amount
        RW.setAmount(ar);

        //Save back to the Map
        ResultList.put(String.valueOf(ar.get('Date')), RW);
    }
}

public List<RevenueWrapper> getResults() {
    return ResultList.values();
}


public class RevenueWrapper{
    public String revenueDate { get; set; }
    public Integer budgetAmount { get; set; }
    public Integer actualAmount { get; set; }
    public Integer varianceFYPercent { set; }
    public Integer varianceFYAmount { set; }

    public RevenueWrapper(){

    }

    public void setAmount(AggregateResult ar){
        revenueDate = String.valueOf(ar.get('Date'));

            //Set the amount value based on type
        if(ar.get('Type__c') == 'Budget'){
            budgetAmount = Integer.valueOf(ar.get('Amount'));
        }else if(ar.get('Type__c') == 'Actual'){
            actualAmount = Integer.valueOf(ar.get('Amount'));
        }else{ //Catch all for a type that isn't recognised
            return;
        }

    }

    public Integer getVarianceFYAmount(){
        return actualAmount - budgetAmount;
    }

    public Decimal getVarianceFYPercent(){
        if(budgetAmount != 0){
            return Decimal.valueOf((Double.valueOf(actualAmount) / Double.valueOf(budgetAmount)) * 100).setscale(1);
        } else{
            return 0;
        }
    }
}

}

There are several ways of doing this.

One would be to sort your GroupBy results using a for loop.

Another would be to put the results into map(s). Then take the top two results from your sorting in order to get them for the respective parents.

Since you're using a GroupBy, you could also presumably return something "like" ar[0].cnt, ar[0].Parent__r.Primary_Category__c and ar[1].cnt, ar[1].Parent__r.Primary_Category__c to get the top two for the parent with the "most" results and compare the two Parent_r's to see if they're the same. If they're not, you have the two that you're looking for that are at the top.

If they are the same, you'll need to test ar[3], ar[4], etc until you find a different Parent__r to assign as the second parent.

From the above, you'll already know the results for the highest Primary_Category__c for the first Parent__r and for the 2nd one as well. Now you need to sort the secondary category based on the what you learned determined to be the 1st and second parents.

I believe this is where you may want to put the results into two maps.

Beginning with the 1st parent, do a for loop to add the results of a loop to the map if the parent and the secondary_category__c matches parent__r that was the 1st parent and secondary_category__c isEmpty() == false. The first result you find will be the one you're looking for. Rather than putting it into a map, you could break from the for loop if you wanted to. the choice would be yours to make.

You'd repeat the same process above for the other parent__r.