I have this nested array:
array = [
["A", "X"],
["B", "Y"],
["C", "Z"]
]
Is there a function that returns "B" when I provide "Y" and "C" when I provide "Z"?
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2Picky-picky point: it would better to change 'and "C"' to 'and return "C"'. Initially I thought you were providing "Y" and "C" and wanted "B", which seemed odd and made the sentence undecipherable. Of course, I may be the only person in the room who read it that way.Cary Swoveland– Cary Swoveland2016-07-25 15:15:07 +00:00Commented Jul 25, 2016 at 15:15
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4 Answers
You can use find method.
array = [
["A", "X"],
["B", "Y"],
["C", "Z"]
]
str = "Y"
arr = array.find{|a| a[1] == str}
puts arr[0] if arr
# => B
Comments
Or, you can convert it to a Hash, if you need to do many lookups and the array is biggish:
hash = array.map(&:reverse).to_h
hash["Y"]
# => "B"
Comments
There is no such internal function out of the box, but one might easily create one:
▶ λ = ->(input) { array.detect { |e| e.last == input }.first rescue nil }
#⇒ #<Proc:0x0000000437f150@(pry):10 (lambda)>
▶ λ.('X')
#⇒ "A"
▶ λ.('Y')
#⇒ "B"
▶ λ.('QQQ')
#⇒ nil
answered Jul 25, 2016 at 8:33
Aleksei Matiushkin
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