ruby - How to compare two key, value pairs embedded in an array? -

if have 2 candidates , 5 voters, , results of tendency vote are:

[   [:john, :clinton, -27],   [:john, :bush, -8],   [:raphael, :clinton, -12],   [:raphael, :bush, -40],   [:damon, :clinton, 71],   [:damon, :bush, 4],   [:elysee, :clinton, 13],    [:elysee, :bush, -36],   [:griffin, :clinton, -1],   [:griffin, :bush, 11] ] 

how @ each voter, , count largest tendency number vote candidate , store in variable final tally of votes per candidate?

hello! , responses. not new programming, i'm new stackoverflow forgive me if i'm not editing properly.

apologies.

reading guys put, don't know them, i'll put code came , try explain better trying achieve. bear me.

if have:

def stump_speech   voter_list = {     john: "progressive",     raphael: "conservative",     damon: "libertarian",     elysee: "independent",     griffin: "massachussetts democrat"   } end 

and comparing to:

candidate_list = {}   candidate_list = {     clinton: "democrat",     bush: "republican", } 

and runs is:

voter_list.each { |voter_name, politics| candidate_list.each { |candidate_name, party|   if     politics == "progressive" && party == "republican"     voting_prob = rand(0..100) - 25     decision   elsif     politics == "progressive" && party == "democrat"     voting_prob = rand(0..100) - 75     decision   elsif     politics == "conservative" && party == "republican"     voting_prob = rand(0..100) - 75     decision   elsif     politics == "conservative" && party == "democrat"     voting_prob = rand(0..100) - 25     decision   elsif     politics == "independent" && party == "republican"     voting_prob = rand(0..100) - 50     decision   elsif     politics == "independent" && party == "democrat"     voting_prob = rand(0..100) - 50     decision   elsif     politics == "libertarian" && party == "republican"     voting_prob = rand(0..100) - 90     decision   elsif     politics == "libertarian" && party == "democrat"     voting_prob = rand(0..100) - 10     decision   elsif     politics == "massachussetts democrat" && party == "republican"     voting_prob = rand(0..100) - 10     decision   elsif     politics == "massachussetts democrat" && party == "democrat"     voting_prob = rand(0..100) - 90     decision   else   end } } 

and outputs array above earlier posted, how grab numbers, john's, example, count vote bush, , raphael's clinton, etc., , throw array play final tally in determining winner?

in simplest way can manage, please? much! i'm ten days , grasping concepts isn't easy yet - hoping not discouraged.

starting following array of arrays:

tendencies = [   [:john, :clinton, -27],   [:john, :bush, -8],   [:raphael, :clinton, -12],   [:raphael, :bush, -40],   [:damon, :clinton, 71],   [:damon, :bush, 4],   [:elysee, :clinton, 13],    [:elysee, :bush, -36],   [:griffin, :clinton, -1],   [:griffin, :bush, 11] ] 

first, use enumerable's group_by organize voter, first entry in each array.

tendencies.group_by {|t| t.first} 

or, equivalently,

tendencies.group_by(&:first) 

this results in following hash:

{   :john    =>[[:john, :clinton, -27], [:john, :bush, -8]],   :raphael =>[[:raphael, :clinton, -12], [:raphael, :bush, -40]]   :damon   =>[[:damon, :clinton, 71], [:damon, :bush, 4]],   :elysee  =>[[:elysee, :clinton, 13], [:elysee, :bush, -36]],   :griffin =>[[:griffin, :clinton, -1], [:griffin, :bush, 11]] } 

now, i'm assuming want 1 candidate per voter. if @ each of values above there 2 options , want 1 max. since want 1 candidate per value, can use map. example, bush votes only, can following:

tendencies.group_by(&:first).values.map(&:last) 

this takes last (second) subarray each line above:

[   [:john, :bush, -8],   [:raphael, :bush, -40],   [:damon, :bush, 4],   [:elysee, :bush, -36],   [:griffin, :bush, 11] ] 

but don't want this, we? want 1 max tendency value. need use max_by. take max based on criteria specify, in case last value of each subarray (the tendency).

tendencies.group_by(&:first).values.map{ |v| v.max_by(&:last)} 

result:

[  [:john, :bush, -8],  [:raphael, :clinton, -12],  [:damon, :clinton, 71],  [:elysee, :clinton, 13],  [:griffin, :bush, 11] ] 

getting closer! can grab middle value (index [1]) of result using map:

tendencies.group_by(&:first).values.map{ |v| v.max_by(&:last)}.map{ |v| v[1]} 

result: [:bush, :clinton, :clinton, :clinton, :bush]

now depends on how want represent final tally. let's want counts per candidate. there a few ways it, i'm going use we've used above, group_by , map.

votes = [:bush, :clinton, :clinton, :clinton, :bush]  votes.group_by{|v| v}  # => {:bush=>[:bush, :bush], :clinton=>[:clinton, :clinton, :clinton]}  votes.group_by{|v| v}.map{|candidate, votes| [candidate, votes.count]}  # => [[:bush, 2], [:clinton, 3]]