R/lag_variable.R

In ThomasWilli/politantheme: Provides a theme for the politan.ch blog

##' Make any data.frame numerical
##'
##' 
##'
##' @export


shift<-function(x,shift_by){
  stopifnot(is.numeric(shift_by))
  stopifnot(is.numeric(x))
  
  if (length(shift_by)>1)
    return(sapply(shift_by,shift, x=x))
  
  out<-NULL
  abs_shift_by=abs(shift_by)
  if (shift_by > 0 )
    out<-c(tail(x,-abs_shift_by),rep(NA,abs_shift_by))
  else if (shift_by < 0 )
    out<-c(rep(NA,abs_shift_by), head(x,-abs_shift_by))
  else
    out<-x
  out
}