slice(at:)

Declaration

@export(implementation) consuming func slice<let indexRank : Int>(at ranges: [indexRank of any NDArray.RangeExpression]) -> NDArray.MutableRawView

Parameters

• ranges:

  The range expressions describing where to slice along each dimension. indexRank must be ≤ rank. Unspecified trailing dimensions are assumed to be .all.

Discussion

For example if you have a 3D NDArray and want to increment a specific region, you can slice that region, reintroduce the scalar type, and then access a span over it (or use withUnsafeMutablePointer if not contiguous).

/// Updates the desired channel and range of rows
func incrementRegion(
  of mutableRawView: consuming NDArray.MutableRawView,
  channel: Int,
  startRow: Int,
  endRow: Int
) {
  var region = mutableRawView.slice(at: [channel, startRow..<endRow, .all]).view(as: Float.self)
  var mutableSpan = region.contiguousElements! // contiguous region expected in this case

  for i in mutableSpan.indices {
    mutableSpan[i] += 1
  }
}