How to access current mapped tuple while mapping a list?

Question

Could someone please help me to avoid duplicate computations in the Scala mapping below?

(for (i <- 0 to 20) yield i).map((i: Int) => (
  math.pow(2, i),
  math.pow(2, i).toString, // duplicate computation
  math.sqrt(i),
  math.sqrt(i).toString    // duplicate computation
))

Answer 1

You don't need the map here and you can introduce new values inside for-comprehension:

for {
   i <- 0 to 20
   pow2 = math.pow(2, i)
   sqrti = math.sqrt(i)
} yield (pow2, pow2.toString, sqrti, sqrti.toString)