R/plotting/stat_step.R

In jstagge/staggefuncs: General Personal Functions for James Stagge

# *------------------------------------------------------------------
# | FUNCTION NAME: StatStepribbon
# | FILE NAME: StatStepribbon.R
# | DATE: 
# | CREATED BY:  Jim Stagge         
# *------------------------------------------------------------------
# | Parameter:
# | 
# |     Desc:      For ggplot2, creates a step plot
# |                
# *------------------------------------------------------------------


stairstepn <- function( data, direction="hv", yvars="y" ) {
  direction <- match.arg( direction, c( "hv", "vh" ) )
  data <- as.data.frame( data )[ order( data$x ), ]
  n <- nrow( data )
  
  if ( direction == "vh" ) {
    xs <- rep( 1:n, each = 2 )[ -2 * n ]
    ys <- c( 1, rep( 2:n, each = 2 ) )
  } else {
    ys <- rep( 1:n, each = 2 )[ -2 * n ]
    xs <- c( 1, rep( 2:n, each = 2))
  }
  
  data.frame(
    x = data$x[ xs ]
    , data[ ys, yvars, drop=FALSE ]
    , data[ xs, setdiff( names( data ), c( "x", yvars ) ), drop=FALSE ]
  ) 
}


stat_stepribbon <- 
  function(mapping = NULL, data = NULL, geom = "ribbon", position = "identity", inherit.aes = TRUE) {
    ggplot2::layer(
      stat = Stepribbon, mapping = mapping, data = data, geom = geom, 
      position = position, inherit.aes = inherit.aes
    )
  }

StatStepribbon <- 
  ggproto("stepribbon", Stat,
          compute_group = function(., data, scales, direction = "hv", yvars = c( "ymin", "ymax" ), ...) {
            stairstepn( data = data, direction = direction, yvars = yvars )
          },                        
          required_aes = c( "x", "ymin", "ymax" )
  )