formatting an entire line in ruby given multiple arguments - ruby

Question

For my program, I have a list of things that's sort of like a spreadsheet that I'm trying to print to the console. I want it to look something like
garage 1
car: jaguar
price: $134,000
car: mercedes
price: $234,000
garage 2
car: jaguar
price: $134,000
garage is a hash with each key being garage number and cars in a specific garage being pushed to each key, eg garage[0] = [car1, car2]
Class car holds the information printed, and has these definitions
class Car
attr_accessor :car_name, :car_price
def initialization(name, price)
#car_name = name
#car_price = price
end
def name
#car_name
end
def price
#car_price
end
end
I've tried to implement such
garage.each do |x|
print "garage "
print garage.index(x) + 1
puts " "
x.each do |y|
printf("%10s", "Car: ")
puts y.name.rjust(16)
printf("%10s", "Price: $")
puts y.price.to_s.rjust(16)
puts " "
end
end
But I'm not getting the desired output. Depending on the car name, the spaces in between will be too far and the output won't be aligned.
I'm wondering if there's a method where I can format an entire line output? Basically like chaining together strings and other variables such as integers and floats and setting their distances correctly so that I can customize each line that's output to console.

Answer 1

First create the Car class:
class Car
attr_accessor :car_name, :car_price
def initialize(name, price)
#car_name = name
#car_price = price
end
end
Note that the method is initialize, not initialization, and that the class method attr_accessor creates both getter and setter methods for each of the two instance variables, so there is no need for the explicit getter methods.
Now let's create a couple of instances of this class.
jag = Car.new('jaguar', 134000)
#=> #<Car:0x00007f839690d2d0 #car_name="jaguar", #car_price=134000>
mb = Car.new('mercedes', 234000)
#=> #<Car:0x00007f83990b1d90 #car_name="mercedes", #car_price=234000>
Suppose the hash garage is as follows.
garage = { 1=>[jag, mb], 2=>[jag] }
#=> {1=>[#<Car:0x00007f839690d2d0 #car_name="jaguar", #car_price=134000>,
#=> #<Car:0x00007f83990b1d90 #car_name="mercedes", #car_price=234000>],
# 2=>[#<Car:0x00007f839690d2d0 #car_name="jaguar", #car_price=134000>]}
Firstly, we will need a way to display car prices in the correct format, starting with a dollar sign and with thousands separated by commas. One way to do that is as follows.
def convert_price_to_str(car_price)
s = ''
loop do
car_price, three = car_price.divmod(1000)
break "$#{three}#{s}" if car_price.zero?
s = (",%03d" % three) + s
end
end
For example,
convert_price_to_str 34 #=> "$34"
convert_price_to_str 3042 #=> "$3,042"
convert_price_to_str 49621 #=> "$49,621"
convert_price_to_str 1324534 #=> "$1,324,534"
See Integer#divmod, a very handy (and underutilized) method.
To display the values in the desired format it is necessary to determine the length of the longest car name or formatted price.
longest = garage.values.flatten.map do |car|
[car.car_name.size, convert_price_to_str(car.car_price).size].max
end.max
#=> 8
Now let's write another helper method to display car names and prices.
def print_name_and_price(name, price, longest)
puts " car: #{name.rjust(longest)}"
puts " price: #{convert_price_to_str(price).rjust(longest)}"
puts
end
For example,
print_name_and_price('jaguar', 134000, longest)
displays the three lines (the last being empty):
car: jaguar
price: $134,000
See String#rjust.
We may now put all this together.
garage.each do |g,cars|
puts "garage #{g}"
cars.each do |car|
print_name_and_price(car.car_name, car.car_price, longest)
end
end
displays:
garage 1
car: jaguar
price: $134,000
car: mercedes
price: $234,000
garage 2
car: jaguar
price: $134,000