R/polyCurve.R

In edseab/Counterfact: Produces counterfactual predictions for an independant variable of interest

polyCurve <- function(x, y, from=min(x), to=max(x), n = 50, miny,
                      col = "red", border = col) {
    drawPoly <- function(fun, from, to, n = 50, miny, col, border) {
        Sq <- seq(from = from, to = to, length = n)
        polygon(x = c(Sq[1], Sq, Sq[n]),
                y = c(miny, fun(Sq), miny),
                col = col, border = border)
    }
    lf <- length(from)
    stopifnot(identical(lf, length(to)))
    if(length(col) != lf)
        col <- rep(col, length.out = lf)
    if(length(border) != lf)
        border <- rep(border, length.out = lf)
    if(missing(miny))
        miny <- min(y)
    interp <- approxfun(x = x, y = y)
    mapply(drawPoly, from = from, to = to, col = col, border = border,
           MoreArgs = list(fun = interp, n = n, miny = miny))
    invisible()
}