access_by_index.nim

import sequtils
proc `[]`*[T](a: openArray[T], inds: seq[int]): seq[T] {.inline.} =
  ## given two openArrays, return a sequence of all elements whose indices
  ## are given in 'inds'
  ## inputs:
  ##    a: seq[T] = the sequence from which we take values
  ##    inds: openArray[int] = the array which contains the indices for the
  ##         arrays, which we take from 'array'
  ## outputs:
  ##    seq[T] = a sequence of all elements s.t. array[ind] in numpy indexing
  result = newSeq[T](inds.len)
  for i, ind in inds:
    result[i] = a[ind]

let a = toSeq(0..100)

echo a[toSeq(countup(3, 50, 7))]