I would like to use the following formula to calculate a Bayesian score for each of my products, based on their scores (0-100) and number of votes:
( (avg_num_votes * avg_rating) + (this_num_votes * this_rating) ) /
(avg_num_votes + this_num_votes)
Each product has_many reviews, and each review has a 'score' which is 0-100.
When pulling the list of products from the database what would be the best approach to calculating the Bayesian score to be listed in a table in the view?
EDIT: I am looking for something along the lines of:
Product.each do |product|
#product_bayesian = ((Review.count * Review.average(:score)) + (product.reviews.count + product.reviews.average(:score))/(Review.count+product.reviews.count)
end
but, done in the most efficient way possible, possibly through a join in the controller?
Here is my solution:
def overall
#products = Product.all
#overall_count = Review.count
#overall_average = Review.average(:score)
#unranked = {}
#products.each do |product|
#review_score_raw = product.reviews.average(:score)
#review_score = #review_score_raw.to_int if #review_score_raw
#review_count = product.reviews.count
if product.reviews.count == 0
#bayesian = 0
else
#bayesian = (((#overall_count * #overall_average) + (#review_count * #review_score_raw))/(#overall_count + #review_count))
end
#unranked[product] = #bayesian
end
#ranked = #unranked.sort_by {|key, value| value}.reverse.each_with_index.to_a
end
Related
Using Rails 6. Here's a piece that I wrote just to display number of stars. Obviously I am disgusted by my own code. How would you refactor?
# application_helper.rb
module ApplicationHelper
def show_star_rating(rating)
zero_star_icon_name = "star"
full_star_icon_name = "star_fill"
half_star_icon_name = "star_lefthalf_fill"
total_stars = []
round_by_half = (rating * 2).round / 2.0
(round_by_half.to_i).times { total_stars << full_star_icon_name }
if round_by_half - round_by_half.to_i == 0.5
total_stars << half_star_icon_name
end
if total_stars.size != 5
(5 - total_stars.size).times { total_stars << zero_star_icon_name }
end
total_stars
end
end
# show.html.erb
<% show_star_rating(agent_review.rating).each do |star| %>
<i class="f7-icons"><%= star %></i>
<% end %>
You can make use of the Array.new, passing in the maximum number of stars you want to show, and defaulting all the stars to empty. Then, you can fill in the number of full stars you need. Then, finally, thanks to Numeric's divmod returning either 0 or 1 for the number of half stars you need, you make one more pass and fill in the number of half stars you need:
module StarHelper
EMPTY_STAR_ICON = 'star'.freeze
FULL_STAR_ICON = 'star_fill'.freeze
HALF_STAR_ICON = 'star_lefthalf_fill'.freeze
def full_and_half_star_count(rating)
(rating * 2).round.divmod(2)
end
def stars(rating, max_stars: 5)
full_stars, half_stars = full_and_half_star_count(rating)
Array.new(max_stars, EMPTY_STAR_ICON).
fill(FULL_STAR_ICON, 0, full_stars).
fill(HALF_STAR_ICON, full_stars, half_stars)
end
end
The way I would implement show_star_rating:
def show_star_rating(rating)
zero_star_icon_name = "star"
full_star_icon_name = "star_fill"
half_star_icon_name = "star_lefthalf_fill"
rating_round_point5 = (rating * 2).round / 2.0
(1..5).map do |i|
next(full_star_icon_name) if i <= rating_round_point5
next(half_star_icon_name) if rating_round_point5 + 0.5 == i
zero_star_icon_name
end
end
I am working on a kind of order where I have multiple amount in different currencies in just one attribute. So am trying to make sum on different currencies inside that attribute using other attributes in the table, which works fine but outputs the result as a count of all the rows instead of just showing the sum of the random values calculated.
orders_controller.rb
module Admin
module Statistic
class OrdersController < BaseController
def show
#orders_grid = ::Statistic::OrdersGrid.new(params[:statistic_orders_grid]) do |value|
value.page(params[:page]).per(20)
end
#assets = #orders_grid.assets
##fee_groups = {:fee => #assets.sum(:fee)}
#fee_groups = {
:fee => #assets.sum{|t|
olaoa = t.type
market_string = t.currency
base_currency = market_string.slice(0..2)
quote_currency = market_string.slice(3..5)
if olaoa == 'OrderBid' and base_currency == 'btc'
"#{ t.fee.to_s + ' ' + base_currency.upcase }"
elsif olaoa == 'OrderAsk' and quote_currency == 'ngn'
"#{ t.fee.to_s + ' ' + quote_currency.upcase }"
end
}
}
#orders_filter = true
#orders_group = true
end
end
end
end
summary.htm.slim
.panel.panel-default
.panel-heading
h4.panel-title.row
a data-parent="#filter-accordion" data-toggle="collapse" href="#summary"
span.col-xs-8.text-muted = t('admin.statistic.summary')
span.col-xs-4.text-right.text-muted = t('admin.statistic.click-to-expand')
#summary.panel-collapse.collapse
.panel-body
.datagrid-groups
- if !#orders_group
- if groups
- groups.each do |key, val|
.datagrid.group.row
span.col-xs-2.title = t("admin.statistic.#{controller_name}.#{controller.action_name}.#{key}")
span.col-xs-10.value = val
- if #orders_group
/ Summary Count Loop
- if groups
- groups.each do |key, val|
.datagrid.group.row
span.col-xs-2.title = t("admin.statistic.#{controller_name}.#{controller.action_name}.#{key}")
span.col-xs-10.value = pluralize(val, 'Order')
/ Summary Fees Loop. This is the Fee loop causing problem if am rigth and I dont know how to fix this.
- if #fee_groups
- #fee_groups.each do |key, val|
.datagrid.group.row
span.col-xs-2.title = t("admin.statistic.#{controller_name}.#{controller.action_name}.#{key}")
span.col-xs-10.value = val
The result of the code
So as you can see it renders 0.0BTC 5 times because the filter only has 5 orders. How do i deal with this. I want just the sum of all BTCs to show in the result instead of showing it 5 times.
Any help will be appreciated.
Because you sum strings in you're #fee_groups query that will results in putting strings next to each other instead of a total amount.
If you call it like this
#fee_groups = { fee: #assets.sum{|t| t.fee}}
You will get the total sum of you're assets.
Let's say i have two relation arrays of a user's daily buy and sell.
how do i iterate through both of them using .each and still let the the longer array run independently once the shorter one is exhaused. Below i want to find the ratio of someone's daily buys and sells. But can't get the ratio because it's always 1 as i'm iterating through the longer array once for each item of the shorter array.
users = User.all
ratios = Hash.new
users.each do |user|
if user.buys.count > 0 && user.sells.count > 0
ratios[user.name] = Hash.new
buy_array = []
sell_array = []
date = ""
daily_buy = user.buys.group_by(&:created_at)
daily_sell = user.sells.group_by(&:created_at)
daily_buy.each do |buy|
daily_sell.each do |sell|
if buy[0].to_date == sell[0].to_date
date = buy[0].to_date
buy_array << buy[1]
sell_array << sell[1]
end
end
end
ratio_hash[user.name][date] = (buy_array.length.round(2)/sell_array.length)
end
end
Thanks!
You could concat both arrays and get rid of duplicated elements by doing:
(a_array + b_array).uniq.each do |num|
# code goes here
end
Uniq method API
daily_buy = user.buys.group_by(&:created_at)
daily_sell = user.sells.group_by(&:created_at
buys_and_sells = daily_buy + daily_sell
totals = buys_and_sells.inject({}) do |hsh, transaction|
hsh['buys'] ||= 0;
hsh['sells'] ||= 0;
hsh['buys'] += 1 if transaction.is_a?(Buy)
hsh['sells'] += 1 if transaction.is_a?(Sell)
hsh
end
hsh['buys']/hsh['sells']
I think the above might do it...rather than collecting each thing in to separate arrays, concat them together, then run through each item in the combined array, increasing the count in the appropriate key of the hash returned by the inject.
In this case you can't loop them with each use for loop
this code will give you a hint
ar = [1,2,3,4,5]
br = [1,2,3]
array_l = (ar.length > br.length) ? ar.length : br.length
for i in 0..array_l
if ar[i] and br[i]
puts ar[i].to_s + " " + br[i].to_s
elsif ar[i]
puts ar[i].to_s
elsif br[i]
puts br[i].to_s
end
end
The real tactical question I am facing is all categories are set as 'default' therefore if I make options[:category] = 'default' it only adds the points that have no category. Therefore if i add points to cateogry 'arin' it will not be counted to the 'default' total. So I tried to grab all tables if NOT NULL or by category but it keeps grabbing the same amount for 'arin'.
default: 20
arin: 20
Should be total of 40 if category not supplied or at 'default', if params category 'arin' then it should be 20.
Can someone help me understand the concept behind the correct SQL to get the results I am looking for?
New to rails and SQL.
def self.top_scored(options = {})
options[:table_name] ||= :users
options[:since_date] ||= 4.months.ago
options[:end_date] ||= 1.month.from_now
options[:category] ||= nil
options[:limit] ||= 10
alias_id_column = "#{options[:table_name].to_s.singularize}_id"
if options[:table_name] == :sashes
sash_id_column = "#{options[:table_name]}.id"
else
sash_id_column = "#{options[:table_name]}.sash_id"
end
# MeritableModel - Sash -< Scores -< ScorePoints
sql_query = <<SQL
SELECT
#{options[:table_name]}.id AS #{alias_id_column},
SUM(num_points) as sum_points
FROM #{options[:table_name]}
LEFT JOIN merit_scores ON merit_scores.sash_id = #{sash_id_column}
LEFT JOIN merit_score_points ON merit_score_points.score_id = merit_scores.id
WHERE merit_score_points.created_at > '#{options[:since_date]}' AND merit_score_points.created_at < '#{options[:end_date]}' AND (merit_scores.category IS NOT NULL OR merit_scores.category = '#{options[:category]}')
GROUP BY #{options[:table_name]}.id, merit_scores.sash_id
ORDER BY sum_points DESC
LIMIT #{options[:limit]}
SQL
results = ActiveRecord::Base.connection.execute(sql_query)
results.map do |h|
h.keep_if { |k, v| (k == alias_id_column) || (k == 'sum_points') }
end
results
end
end
Seems no one answered and only down voted. Here is to anyone that questions this in the future. I figured out you can split sql statements and use an if statement in rails around the SQL.
sql_query = "SELECT
#{options[:table_name]}.id AS #{alias_id_column},
SUM(num_points) as sum_points
FROM #{options[:table_name]}
LEFT JOIN merit_scores ON merit_scores.sash_id = #{sash_id_column}
LEFT JOIN merit_score_points ON merit_score_points.score_id = merit_scores.id
WHERE merit_score_points.created_at > '#{options[:since_date]}' AND merit_score_points.created_at < '#{options[:end_date]}' "
if(options[:category] != nil)
sql_query += "AND merit_scores.category = \"#{options[:category]}\" "
end
sql_query += "GROUP BY #{options[:table_name]}.id, merit_scores.sash_id
ORDER BY sum_points DESC
LIMIT #{options[:limit]} "
results = ActiveRecord::Base.connection.execute(sql_query)
I have created a loop, to calculate a total rating of a record. To do this I am first looping through all the child records (ratings), extracting the rating from each row, adding it to the total and then outputting the total.
<% total = 0 %>
<% for ratings in #post.ratings %>
<% total = (total + ratings.rating) %>
<% end %>
<%= total %>
My question is, simply, Is this the rails way?
It achieves the desired result, although needs 5 lines to do so. I am worried I am bring old habits from other languages into my rails project, and I am hoping someone could clarify if there is an easier way.
The following, preferably in the controller, will do it succinctly:
#rating = #post.ratings.sum { &:rating }
If that seems cryptic, you might prefer
#rating = #post.ratings.inject(0) { |sum, p| sum + p.rating }
Note, however, that this will fail if any of the ratings are null, so you might want:
#rating = #post.ratings.inject(0) { |sum, p| sum + (p.rating || 0) }
You should generally keep logic out of your views. I would put that code in a helper or a controller, and the call a method to calculate the total
Put the following in your controller, then you just need to use #rating in your view:
total = 0
#rating = #post.ratings.each { |r| total += r.rating }
Or you could move it into the Post model and do something like:
def self.total_rating
total = 0
ratings.each { |r| total += r.rating }
total
end
and then simply call #post.total_rating