Improve analytics readability

The histogram needed to identify that there are N events in the X to Y group.
Similarly, a frequency is an integer: there are no 1.3 observations of "slept
between 2 and 3 hours".

app.rb

@@ -185,11 +185,11 @@ def table_name_from_user_id(user_id)
     GROUP BY 1, 2
   EOSQL
   @hours_slept_histogram = hours_slept_histogram_ds.to_hash_groups([:sleep_type, :hour], :count).map do |key, value|
-    [[key.first, key.last.to_f], value.first.to_f]
+    [[key.first, key.last.to_f], value.first]
   end.to_h
   @max_hours = Hash.new
-  @max_hours["night"] = @hours_slept_histogram.select{|k, _| k[0] == "night"}.map(&:last).compact.sort.last.to_f
-  @max_hours["nap"]   = @hours_slept_histogram.select{|k, _| k[0] == "nap"}.map(&:last).compact.sort.last.to_f
+  @max_hours["night"] = @hours_slept_histogram.select{|k, _| k[0] == "night"}.map(&:last).compact.sort.last
+  @max_hours["nap"]   = @hours_slept_histogram.select{|k, _| k[0] == "nap"}.map(&:last).compact.sort.last
 
   @user_id = user_id
   @app = :analytics

views/analytics.erb

@@ -39,7 +39,7 @@
           <% (0..23).each do |hour| %>
             <% next unless @hours_slept_histogram[[key, hour.to_f]] %></td>
             <tr>
-              <td><%= hour %></td>
+              <td><%= hour %> - <%= hour + 1 %></td>
               <td><%= @hours_slept_histogram.fetch([key, hour.to_f], "N/A") %></td>
               <td>
                 <div class="graph-bar" style="width: <%= "%.1f" % [ 100.0 * @hours_slept_histogram.fetch([key, hour.to_f], 0.0) / @max_hours.fetch(key, 1.0) ] %>%">&nbsp;</div>