Making a CSV file into a hash and then grouping by criteria

Question

In ruby, if I have a CSV file that looks like this:

make,model,color,doors                                  
dodge,charger,black,4               
ford,focus,blue,5          
nissan,350z,black,2             
mazda,miata,white,2             
honda,civid,brown,4            
corvette,stingray,red,2            
ford,fiesta,blue,5

how would I be able to change this to a hash and be able to group them together by amount of doors or another parameter from the header, for example, the program asks the user for the amount of doors, if the user enters "2" then only the lines that have "2" for doors will be outputted (please comment)

Answer 1

I don't believe a hash table is what you want as you would have to make a new one for each attribute. Here's a way of doing it using a Car class

    require "csv"
    
    
    class Car
        attr_accessor :make, :model, :color,:door
    
        def initialize(make, model, color, door)
            @make, @model, @color, @door = make, model, color, door
        end
    
        def to_s
            "Make: #{self.make}, Model: #{self.model}, Color: #{self.color}, Door: #{door}"
        end
    end
    
    cars = CSV.read("so.csv").map{|car| Car.new(car[0], car[1], car[2], car[3])}
    
    attributeWanted = gets.chomp
    value = gets.chomp
    
    
    wantedCars = cars.select{|car| car.instance_variable_get("@#{attributeWanted}") == value}
    puts(wantedCars)

Result: door 5 Make: ford, Model: focus, Color: blue, Door: 5 Make: ford, Model: fiesta, Color: blue, Door: 5