I have an array which contains numbers and alphabets something like:
newArray = ["1 a", "1 b" ,"2 c", "2 a"]
I would like to sort them in a way that the output is expected as follows:
newArray = ["2 a", "2 c" ,"1 a", "1 b"]
What I want to do is sort the numbers in descending order and if the numbers are same, then sort alphabetically
Can I implement a comparison function in sort_by or is there a way to do that using ruby sort
First you should use a better representation of your input. You can parse your existing array for example like this:
arr = newArray.map { |s| x,y = s.split; [x.to_i, y] }
# => [[1, "a"], [1, "b"], [2, "c"], [2, "a"]]
Then we can sort as we wish using sort_by:
arr.sort_by { |x,y| [-x, y] }
# => [[2, "a"], [2, "c"], [1, "a"], [1, "b"]]
String#%. That said, I recomment not using strings to represent a tuple of values. You will lose type safety and handling of the strings will be awkward (as you can see, even for this simple application we need to parse the strings anyway)
arr= arr.sort_by { |x,y| [-x, y] } then do arr.map{|a| a=a.join(" ")}Similar to @NiklasB. 's answer above (copied his sort_by)
arr.map(&:split).sort_by { |x,y| [-x.to_i, y] }
=> [["2", "a"], ["2", "c"], ["1", "a"], ["1", "b"]]
In a less elegant way, you can do that
arr.sort! do |p1, p2|
num1, str1 = p1.split(' ')
num2, str2 = p2.split(' ')
if (num1 != num2)
p2 <=> p1
else
p1 <=> p2
end
end
$stdout.puts arr
