Ruby sorting multiple values

Question

I got a little problem trying to sort the given of prices and products.

arr = [[6,"iPhone"],[4,"Android"],[5,"iPhone"],[3,"Xbox"],
       [9,"Android"],[8,"Xbox"]]

But i need to sort it by product and then by price. I make the next common to do it:

arr.sort_by! {|x| [x[1],x[0]]}.reverse
 => [[6, "iPhone"], [5, "iPhone"], [8, "Xbox"], [3, "Xbox"], 
     [9, "Android"], [4, "Android"]]

But i need again to sort it now by the block of products to get the most expensive one block first and so on. The result that I'm looking for its like:

arr = [[9,"Android"],[4,"Android"],[8,"Xbox"],[3,"Xbox"],
       [6,"iPhone"],[5,"iPhone"]]

Any help will be appreciated!

Update 1 I have tested Dave's answer and its works but on other set of items i didn't get the right sort of the block of products.

arr = [[6.0,"iPad 2"], [7, "Mints"], [6.0, "Nerf Crossbow"], [4.5, "iPad 2"],
[6, "Mints"], [6.75, "Nerf Crossbow"], [6.0, "iPad 2"], [5, " Mints"],
[9.0, "Nerf Crossbow"]]

I got this result:

1.9.2p320 :5 >   arr.sort! { |a, b| (a[1] <=> b[1]).nonzero? || b[0] <=> a[0] }  
=> [[7, "Mints"], [6, " Mints"], [5, "Mints"], [9.0, "Nerf Crossbow"], 
[6.75, "Nerf Crossbow"], [6.0, "Nerf Crossbow"], [6.0, "iPad 2"], [6.0, "iPad 2"], 
[4.5, "iPad 2"]]

The problem is that i was expecting

[[9.0, "Nerf Crossbow"], [6.75, "Nerf Crossbow"], [6.0, "Nerf Crossbow"],
[7, "Mints"], [6, "Mints"], [5, "Mints"],[6.0, "iPad 2"], [6.0, "iPad 2"],
[4.5, "iPad 2"]]

Marc-André Lafortune · Accepted Answer · 2012-07-23 00:34:09Z

4

Simple, just negate the price:

arr.sort_by! {|price, product| [product.downcase, -price]}

This is clearer and faster than using sort. I added downcase to the product name as you probably shouldn't care about the case.

answered Jul 23, 2012 at 0:34

Marc-André Lafortune

79.8k17 gold badges172 silver badges167 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Dave Newton Over a year ago

It gives a wildly different result, however.

Marc-André Lafortune Over a year ago

@DaveNewton: Oups, didn't notice I needed to reverse the order of the elements. Fixed.

Andrew Marshall Over a year ago

+1 Far clearer what's going on here and doesn't introduce excessive logic.

Ryan LeCompte · Accepted Answer · 2012-07-23 00:36:18Z

3

Here's another option:

arr.sort_by { |e| [e[1], -e[0]] }

answered Jul 23, 2012 at 0:36

Ryan LeCompte

4,3211 gold badge17 silver badges14 bronze badges

Collectives™ on Stack Overflow

Ruby sorting multiple values

2 Answers 2

3 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

3 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related