Looping Multiple Arrays by year

Question

I'm looking multiple arrays but having trouble with aligning them in a table based on year. At the moment the data doesn't line up with the corresponding year, if data exists in any year it just places the data at the first row, then places '0' data for the rest, ie. not aligning with the year.

View

<table>
<% @a.zip(@b, @c, @d) do |a, b, c, d| %>
 <tr>
  <td><%= a.year %></td>
  <% if a.blank? %>
    <td>0</td>
    <td>0</td>
  <% else %>
    <td><%= a.id %></td>
    <td><%= a.data %></td>
  <% end %>
  <% if b.blank? %>
    <td>0</td>
    <td>0</td>
  <% else %>
    <td><%= b.id %></td>
    <td><%= b.data %></td>
  <% end %>
  <% if c.blank? %>
    <td>0</td>
    <td>0</td>
  <% else %>
    <td><%= c.id %></td>
    <td><%= c.data %></td>
  <% end %>
  <% if d.blank? %>
    <td>0</td>
    <td>0</td>
  <% else %>
    <td><%= d.id %></td>
    <td><%= d.data %></td>
  <% end %>
 </tr>
</table>

Controller

@a = Result.where(id: params[:id_select]).group('year').where('data > 0').select('AVG(data) AS data, year as year, COUNT(id) AS id').order('year ASC')

@b = Result.where(id: params[:id_select]).group('year').where('data > 0').select('AVG(data) AS data, year as year, COUNT(id) AS id').where('id = ?', '0').order('year ASC')

@c = Result.where(id: params[:id_select]).group('year').where('data > 0').select('AVG(data) AS data, year as year, COUNT(id) AS id').where('id = ?', '1').order('year ASC')

@d = Result.where(id: params[:id_select]).group('year').where('data > 0').select('AVG(data) AS data, year as year, COUNT(id) AS id').where('id = ?', '2').order('year ASC')

Answer 1

I think you can try this way. in this you have not need to check for blank values. i hope @a contains all your available years otherwise you needs to merge all years an loop through years

<table>
<% @a.each do |a| %>
 <tr>
  <td><%= a.year %></td>
    <td><%= (a.id || 0 rescue 0) %></td>
    <td><%= (a.data || 0 rescue 0) %></td>
    <td><%= (@b.select{|h| h if h["year"] == a.year }.first.id || 0 rescue 0) %></td>
    <td><%= (@b.select{|h| h if h["year"] == a.year }.first.data || 0 rescue 0 ) %></td>
    <td><%= (@c.select{|h| h if h["year"] == a.year }.first.id || 0 rescue 0) %></td>
    <td><%= (@c.select{|h| h if h["year"] == a.year }.first.data || 0 rescue 0) %></td>
    <td><%= (@d.select{|h| h if h["year"] == a.year }.first.id || 0 rescue 0) %></td>
    <td><%= (@d.select{|h| h if h["year"] == a.year }.first.data || 0 rescue 0) %></td>
 </tr>
<% end %>
</table>

If your @a not contains all years then just try to merge it by

years = ((@a.collect{|h| h["year"]}) + (@b.collect{|h| h["year"]}) + (@c.collect{|h| h["year"]}) + (@d.collect{|h| h["year"]})).uniq

then you can just looping through years array as:

<% years.each do |year| %>
     <tr>
      <td><%= year %></td>
        <td><%= (@a.select{|h| h if h["year"] == year }.first.id || 0 rescue 0) %></td>
        <td><%= (@a.select{|h| h if h["year"] ==  year }.first.data || 0 rescue 0 ) %></td>
        <td><%= (@b.select{|h| h if h["year"] == year }.first.id || 0 rescue 0) %></td>
        <td><%= (@b.select{|h| h if h["year"] ==  year }.first.data || 0 rescue 0 ) %></td>
        <td><%= (@c.select{|h| h if h["year"] == year }.first.id || 0 rescue 0) %></td>
        <td><%= (@c.select{|h| h if h["year"] == year }.first.data || 0 rescue 0) %></td>
        <td><%= (@d.select{|h| h if h["year"] == year }.first.id || 0 rescue 0) %></td>
        <td><%= (@d.select{|h| h if h["year"] == year }.first.data || 0 rescue 0) %></td>
     </tr>
    <% end %>
    </table>

Answer 2

You probably mean this in your view:

<%
  A = @a.group_by{|a| a.year}
  B = @b.group_by{|b| b.year}
  C = @c.group_by{|c| c.year}
  D = @d.group_by{|d| d.year}
%>

<table>
  <% A.each do |year, a| %>
    <% b = B[year] %>
    <% c = C[year] %>
    <% d = D[year] %>
    <tr>
      <td><%= year %></td>
      <% if a.blank? %>
        <td>0</td>
        <td>0</td>
      <% else %>
        <%= a.id %>
        <%= a.data %>
      <% end %>
      <% if b.blank? %>
        <td>0</td>
        <td>0</td>
      <% else %>
        <td><%= b.id %></td>
        <td><%= b.data %></td>
      <% end %>
      <% if c.blank? %>
        <td>0</td>
        <td>0</td>
      <% else %>
        <td><%= c.id %></td>
        <td><%= c.data %></td>
      <% end %>
      <% if d.blank? %>
        <td>0</td>
        <td>0</td>
      <% else %>
        <td><%= d.id %></td>
        <td><%= d.data %></td>
      <% end %>
    </tr>
  <% end %>
</table>

I assume here @a contains all the years other arrays may contain (based on query). If it's not the case, then you first need to create full array of years:

<% years = (A.keys + B.keys + C.keys + D.keys).uniq %>
<table>
  <% years.each do |year| %>
    <% a = A[year] %>
    <!-- the rest is the same, as above -->
  <% end %>
</table>