Replacing values in a byte type NArray in Ruby

Question

I am looking for a way to replace all occurrences of 'A' with 1, 'T' with 2, 'C' with 8, and 'G' with 16 in a byte array. How can this be done?

Answer 1

require "narray"

class NArray
  def cast(type)
    a = NArray.new(type,*self.shape)
    a[] = self
    a
  end
end

conv = NArray.int(256)
atcg = NArray.to_na('ATCG', NArray::BYTE).cast(NArray::LINT)
conv[atcg] = [1,2,8,16]

seq_str = 'ABCDAGDE'
seq_ary = NArray.to_na(seq_str, NArray::BYTE).cast(NArray::LINT)

p conv[seq_ary]
#=> NArray.int(8):
#   [ 1, 0, 8, 0, 1, 16, 0, 0 ]

Answer 2

Is it what you are looking for?

h = {'A' => 1, 'T' => 2, 'C' => 8, 'G' => 16}
a = ['A', 'B', 'C', 'D', 'A', 'G', 'D', 'E']

result = a.map {|c| h.include?(c) ? h[c] : c }