Ruby: Sorting 2 arrays using values from one of them

Question

I\'m creating a simple game in ruby, and I have two arrays storing high score: $HS_Points and $HS_Names. I\'m saving high score in two files, and I wan

Answer 1

Something like this?

names = ['Alice', 'Bob', 'Carol']
points = [22, 11, 33]

Zip

You may want the Array#zip method:

pairs = names.zip(points)
#=> [["Alice", 22], ["Bob", 11], ["Carol", 33]]

Sort

To sort by an array field, compare two fields of the pair.

Sort by name:

pairs.sort{|x,y| x[0] <=> y[0] }  
#=> [["Alice", 22], ["Bob", 11], ["Carol", 33]]

Sort by score:

pairs.sort{|x,y| x[1] <=> y[1] }  
#=> [["Bob", 11], ["Alice", 22], ["Carol", 33]]

Sort By

Another way to sort is the #sort_by method instead of a comparison block (thanks to Niklas B.)

Sort by name:

pairs.sort_by(&:first) 
#=> [["Alice", 22], ["Bob", 11], ["Carol", 33]]

Sort by score:

pairs.sort_by(&:last)
#=> [["Bob", 11], ["Alice", 22], ["Carol", 33]]

Select

To select just the players above a high score:

pairs.select{|x| x[1] >20 }
#=> [["Alice", 22], ["Carol", 33]]

Unzip

To unzip:

pairs.map(&:first)
#=> ["Alice", "Bob", "Carol"]

pairs.map(&:last)
#=> [22, 11, 33]

These ideas may point you in the right direction.

Answer 2

Don't store the names and the scores in separate variables; they're tied together, so their data should be tied togeher.

Try, say, $HighScores, which is an array of hashes with a :name element and a :value element, like:

$HighScores = [  
   { :name => "Bob", :score => 234 },
   { :name => "Mark", :score => 2 },   
]

Then you can add a high score:

$HighScores << { :name => "New Guy", :score => 50000 }

and then re-sort them and take the top 10 in one statement:

$HighScores = $HighScores.sort { |a,b| b[:score] <=> a[:score] }[0,10] 

This will still work if the scores are base-23 encoded. (but why are you doing that?)

You should probably also save them to a single file. To make that easier, consider using the Marshal module.