ruby - Sorting multiple values by ascending and descending -

i'm trying sort array of objects based upon different attributes. of attributes sort in ascending order , in descending order. have been able sort ascending or descending have been unable combine two.

here simple class working with:

class dog   attr_reader :name, :gender    dogs = []    def initialize(name, gender)     @name = name     @gender = gender     dogs << self   end    def self.all     dogs   end    def self.sort_all_by_gender_then_name     self.all.sort_by { |d| [d.gender, d.name] }   end end 

i can instantiate dogs sorted later.

@rover = dog.new("rover", "male") @max = dog.new("max", "male") @fluffy = dog.new("fluffy", "female") @cocoa = dog.new("cocoa", "female") 

i can use sort_all_by_gender_then_name method.

dog.sort_all_by_gender_then_name => [@cocoa, @fluffy, @max, @rover] 

the array returns includes females first, males, sorted name in ascending order.

but if want have gender descending, , name ascending, males first , sorted name ascending. in case:

=> [@max, @rover, @cocoa, @fluffy] 

or, if wanted gender ascending, name descending:

=> [@fluffy, @cocoa, @rover, @max] 

when sorting numerical values, can prepend - make sort in reverse. however, have been unable find way strings. or ideas appreciated. thanks.

here's 1 way using .sort instead of .sort_by:

dogs = [   { name: "rover", gender: "male" },   { name: "max", gender: "male" },   { name: "fluffy", gender: "female" },   { name: "cocoa", gender: "female" } ]  # gender asc, name asc p(dogs.sort |a, b|   [a[:gender], a[:name]] <=> [b[:gender], b[:name]] end)  # gender desc, name asc p(dogs.sort |a, b|   [b[:gender], a[:name]] <=> [a[:gender], b[:name]] end)  # gender asc, name desc p(dogs.sort |a, b|   [a[:gender], b[:name]] <=> [b[:gender], a[:name]] end) 

output:

[{:name=>"cocoa", :gender=>"female"}, {:name=>"fluffy", :gender=>"female"}, {:name=>"max", :gender=>"male"}, {:name=>"rover", :gender=>"male"}] [{:name=>"max", :gender=>"male"}, {:name=>"rover", :gender=>"male"}, {:name=>"cocoa", :gender=>"female"}, {:name=>"fluffy", :gender=>"female"}] [{:name=>"fluffy", :gender=>"female"}, {:name=>"cocoa", :gender=>"female"}, {:name=>"rover", :gender=>"male"}, {:name=>"max", :gender=>"male"}] 

basically, doing similar negating numbers (as mentioned in question), swapping property other element if needs sorted in descending order.