ruby - Reorder array based on passed in value

Question

If I have this array:

["A", "B", "C", "D"]

I have this string:

"C"

I want to reorder the array to look like this:

["C", "A", "B", "D"]

So, the passed in string will move the matching element to the front of the list.

Answer 1

a = ['A', 'B', 'C', 'D', 'C']
target = 'C'

a.partition { |e| e==target }.reduce(:+)
  #=> ["C", "C", "A", "B", "D"]

or

a.select { |e| e==target }.concat(a.reject { |e| e==target })
  #=> ["C", "C", "A", "B", "D"]

a is not modified.