Question

初学者。有一个自定义类方法，可以计算team_a和team_b相互比赛的获胜概率。在我看来，我想显示那些计算。试着将这个与我对其运作方式的有限理解结合在一起。

# team.rb
class Team
  attr_reader :home_team_win_probability, :away_team_win_probability
  def self.matchup(home_team, away_team)
    home_team_win_probability = (home_team.rating - home_team.rating * away_team.rating) / (home_team.rating) + away_team.rating - 2 * home_team.rating * away_team.rating)
    away_team_win_probability = 1 - home_team_win_probability
  end
end

# teams_controller.rb
class TeamsController < ApplicationController
  def matchups
    @team_a = Team.find_by(rank: 2)
    @team_b = Team.find_by(rank: 1)
    @matchup = Team.matchup(@team_a, @team_b)
  end
end

# matchups.html.erb
<h4>Matchup: <%= @team_a.name %> @ <%= @team_a.name %></h4>
# want to do something like this: 
<h5>Home Team Win Probability: <%= @matchup.home_team_win_probability %> </h5>
<h5>Away Team Win Probability: <%= @matchup.away_team_win_probability %> </h5>

@matchup.home_team_win_probability产生错误，因为@matchup只返回最后一行（在这种情况下是客队概率）@matchup.home_team_win_probability => undefined method home_team_win_probability for #<BigDecimal:0x007f860872b3f8

如何在我的自定义类方法中调用home_team_win_probability和away_team_win_probability？感谢。

Answer 1

改为返回哈希：

def self.matchup(home_team, away_team)
    home_team_win_probability = (home_team.rating - home_team.rating * away_team.rating) / (home_team.rating) + away_team.rating - 2 * home_team.rating * away_team.rating)
    away_team_win_probability = 1 - home_team_win_probability
    {home: home_team_win_probability, away: away_team_win_probability}
end

然后访问：

@matchup[:home]
@matchup[:away]

Answer 2

匹配逻辑需要在Team模型中没有特殊原因。我会创建一个新模型......

class Matchup
  attr_accessor :home_team, :away_team
  def initialize(home_team, away_team)
    @home_team = home_team
    @away_team = away_team
  end
  def home_team_win_probability
    (home_team.rating - home_team.rating * away_team.rating) / (home_team.rating) + away_team.rating - 2 * home_team.rating * away_team.rating)
  end
  def away_team_win_probability 
    1 - home_team_win_probability
  end
end

现在，您可以在TeamsController ...

中执行此操作

@matchup = Matchup.new(@team_a, @team_b)

这为您提供了方法@matchup.home_team_probability和@matchup.away_team_probability

从rails中的自定义类方法调用变量

2 个答案: