#' Add function equation to statistical smoothing
#'
#' @inheritParams ggplot2::stat_smooth
#' @param xpos X-position for text
#' @param ypos Y-position for text
#' @source https://gist.github.com/kdauria/524eade46135f6348140
#' @author kdauria
#' @section Computed variables:
#' \describe{
#' \item{y}{predicted value}
#' \item{ymin}{lower pointwise confidence interval around the mean}
#' \item{ymax}{upper pointwise confidence interval around the mean}
#' \item{se}{standard error}
#' }
stat_smooth_func <- function(mapping = NULL, data = NULL,
geom = "smooth", position = "identity",
...,
method = "auto",
formula = y ~ x,
se = TRUE,
n = 80,
span = 0.75,
fullrange = FALSE,
level = 0.95,
method.args = list(),
na.rm = FALSE,
show.legend = FALSE,
inherit.aes = TRUE,
xpos = NULL,
ypos = NULL) {
layer(
data = data,
mapping = mapping,
stat = StatSmoothFunc,
geom = geom,
position = position,
show.legend = show.legend,
inherit.aes = inherit.aes,
params = list(
method = method,
formula = formula,
se = se,
n = n,
fullrange = fullrange,
level = level,
na.rm = na.rm,
method.args = method.args,
span = span,
xpos = xpos,
ypos = ypos,
...
)
)
}
StatSmoothFunc <- ggproto(
"StatSmooth", Stat,
setup_params = function(data, params) {
# Figure out what type of smoothing to do: loess for small datasets,
# gam with a cubic regression basis for large data
# This is based on the size of the _largest_ group.
if (identical(params$method, "auto")) {
max_group <- max(table(data$group))
if (max_group < 1000) {
params$method <- "loess"
} else {
params$method <- "gam"
params$formula <- y ~ s(x, bs = "cs")
}
}
if (identical(params$method, "gam")) {
params$method <- mgcv::gam
}
params
},
compute_group = function(data, scales, method = "auto", formula = y~x,
se = TRUE, n = 80, span = 0.75, fullrange = FALSE,
xseq = NULL, level = 0.95, method.args = list(),
na.rm = FALSE, xpos=NULL, ypos=NULL) {
if (length(unique(data$x)) < 2) {
# Not enough data to perform fit
return(data.frame())
}
if (is.null(data$weight)) data$weight <- 1
if (is.null(xseq)) {
if (is.integer(data$x)) {
if (fullrange) {
xseq <- scales$x$dimension()
} else {
xseq <- sort(unique(data$x))
}
} else {
if (fullrange) {
range <- scales$x$dimension()
} else {
range <- range(data$x, na.rm = TRUE)
}
xseq <- seq(range[1], range[2], length.out = n)
}
}
# Special case span because it's the most commonly used model argument
if (identical(method, "loess")) {
method.args$span <- span
}
if (is.character(method)) method <- match.fun(method)
base.args <- list(quote(formula), data = quote(data), weights = quote(weight))
m <- do.call(method, c(base.args, method.args))
m.rmse <- (sqrt( sum(m$residuals^2) / (length(m$residuals) - 1)) /
mean(m$fitted.values)) * 100
eq <- substitute(atop(italic(y) == b %.% italic(x) + a),
list(
a = as.numeric(format(coef(m)[1], digits = 3)),
b = as.numeric(format(coef(m)[2], digits = 3))
))
func_string = as.character(as.expression(eq))
if(is.null(xpos)) xpos = min(data$x)*0.9
if(is.null(ypos)) ypos = max(data$y)*0.9
data.frame(x=xpos, y=ypos, label=func_string)
},
required_aes = c("x", "y")
)
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.