Matrix-type grid - HELP!

Rails
1

Hi all, I have a billing application in which I want to create a
matrix-type view of period billings by accounting number and by
period. It’s almost working, but not quite, and I’m not Rails-savvy
enough to take it further. Can anyone point me in the right
direction? Thanks in advance! -Katie

The app is on github so you can see the models, joins, etc:
https://github.com/sdstoic/billing/tree/master/app

CONTROLLER (period_billings):

def period_billings
@sla = Sla.find(params[:sla_id])
@current_period = PeriodCounter.first.period.pe_number
@period_billings = @sla.period_billings.sort_by { |pb|
[pb.period.pe_number, pb.general_ledger.general_ledger_number] }
@billings = Array.new(@period_billings.collect { |pb|
pb.general_ledger.general_ledger_number }).uniq.sort_by { |gl| gl }
@periods = Period.where(“fiscal_year = ?”, @sla.fiscal_year)
@general_ledgers = GeneralLedger.sla_related
@total_period_billings =
@sla.period_billings.group_by(&:general_ledger_id)
#@sum_current_amt =
@sla.period_billings.sum(current_amt).group_by(&:general_ledger_id)
respond_to do |format|
format.html # index.html.erb
format.xml { render :xml => @period_billings }
end
end

VIEW (_period_billings.html.erb):

<% @cumulative_total = 0 %>

<% @general_ledgers.each do |g| %> <% end %> <% @period_billings.group_by(&:general_ledger_id).each do |pb| %> <% pb[1].each do |p| %> <% end %> <% end %>
Period <%= g.general_ledger_number %> Total % Expended
<%= pb[1].first.period.pe_number %> <% @sum_current_amt = pb[1].inject(0){|sum,p| sum + p.current_amt.to_i} %> <%= number_to_currency(@sum_current_amt) %> <% @cumulative_total = @cumulative_total + pb[1].inject(0){| sum,billing| sum+billing.current_amt.to_i} %> <%= number_to_currency( @cumulative_total ) %> <%= number_to_currency((@cumulative_total/ @sla.project_total)*100) %> %