R/plot.ece.R

In comparison: Multivariate Likelihood Ratio Calculation and Evaluation

#' An S3 plot method for objects of class `ece`
#' 
## This function will produce an empirical cross entropy plot (ECE plot).
#'
#' @param x an S3 object of class `ece` which is generated from [calc.ece()].
#' @param \dots other arguments that are passed to the `plot` generic.
#' 
#' @author David Lucy
#' 
#' @seealso [calc.ece()]
#' 
#' @importFrom graphics abline legend mtext par plot points
#' 
#' @export
plot.ece = function(x, ...) {
    
    
    # get rid of these eventually
    par(oma = c(0, 0, 0, 0))
    par(mar = c(5, 5, 1, 1))
    par(las = 1)
    
    # eventually make these user selectable
    null.colour = "black"
    ece.colour = "red"
    calibrated.colour = "blue"
    colours.vec = c(null.colour, ece.colour, calibrated.colour)
    
    
    legend.text = c("null", "observed", "calibrated")
    
    
    # dereference all the bits from the ece object
    prior = x$prior
    ece.null = x$ece.null
    ece = x$ece
    ece.cal = x$ece.cal
    
    x.ordinates = log10(prior/(1 - prior))
    legend.x.position = x.ordinates[1]
    
    x.axis.text = expression(paste(log[10], Odds(theta)))
    y.axis.text = "empirical cross entropy"
    
    max.y = max(c(ece.null, ece, ece.cal))
    
    plot(x.ordinates, ece.null, col = null.colour, ylim = c(0, max.y), type = "l", xlab = "", ylab = "", ...)
    
    points(x.ordinates, ece, col = ece.colour, type = "l")
    points(x.ordinates, ece.cal, col = calibrated.colour, type = "l")
    
    mtext(text = x.axis.text, side = 1, line = 2.5, cex = 1.2)
    mtext(text = y.axis.text, side = 2, line = 2.8, cex = 1.2, las = 0)
    
    legend(legend.x.position, max.y, legend = legend.text, col = colours.vec, lty = 1, bty = "n")
    
    
    abline(h = 0, lty = 3)
    abline(v = 0, lty = 3)
}