R/reversals.R

In haberdashPI/wright.lab.util: A set of utilitiy functions used in our lab.

reversals <- function(deltas){
  n = length(deltas)
  delta.changes = deltas[2:n] - deltas[1:(n-1)]
  non.zero.indices = which(abs(delta.changes) > 0)
  non.zero.changes = delta.changes[non.zero.indices]

  m = length(non.zero.changes)
  if(m <= 1){
      NULL
  }else{
    reversals =
      which((non.zero.changes[2:m] * non.zero.changes[1:(m-1)]) < 0)

    deltas[ non.zero.indices[reversals+1]]
  }
}