Added new function geom_curve

Author: veraanadi

DESCRIPTION

@@ -96,6 +96,7 @@ Collate:
     'geom-blank.r'
     'geom-boxplot.r'
     'geom-crossbar.r'
+    'geom-curve.r'
     'geom-defaults.r'
     'geom-dotplot.r'
     'geom-error.r'

NAMESPACE

@@ -224,6 +224,7 @@ export(geom_boxplot)
 export(geom_contour)
 export(geom_count)
 export(geom_crossbar)
+export(geom_curve)
 export(geom_density)
 export(geom_density2d)
 export(geom_dotplot)

NEWS

@@ -50,6 +50,8 @@ ggplot2 1.0.1.9000
 * Improved documentation for `aes()` and many geoms and scales. I've tried
   to reduce the use of `...` so that you can see all the documentation in one
   place rather than having to navigate through multiple pages.
+* Added new function geom_curve to add curved lines to plot (similar to
+  geom_segment to add straight lines). (@veraanadi)
 
 ggplot2 1.0.1
 ----------------------------------------------------------------

R/geom-curve.r

@@ -0,0 +1,64 @@
+#' Single curved line segments.
+#'
+#' @section Aesthetics:
+#' \Sexpr[results=rd,stage=build]{ggplot2:::rd_aesthetics("geom", "curve")}
+#'
+#' @inheritParams geom_point
+#' @param curvature see curveGrob
+#' @param angle see curveGrob
+#' @param ncp see curveGrob
+#' @param arrow specification for arrow heads, as created by arrow()
+#' @param lineend Line end style (round, butt, square)
+#' @seealso \code{\link{geom_segment}}, \code{\link{geom_path}} and \code{\link{geom_line}} for multi-
+#' segment lines and paths.
+#' @export
+#' @examples
+#' # Adding curve segments
+#' library(grid) # needed for arrow function
+#' b <- ggplot(mtcars, aes(wt, mpg)) + geom_point()
+#' b + geom_curve(aes(x = 2, y = 15, xend = 2, yend = 25, curvature = 0.2))
+#' b + geom_curve(aes(x = 2, y = 15, xend = 3, yend = 15, ncp = 2))
+#' b + geom_curve(aes(x = 5, y = 30, xend = 3.5, yend = 25), arrow = arrow(length = unit(0.5, "cm")))
+
+
+geom_curve <- function (mapping = NULL, data = NULL, stat = "identity",
+                        position = "identity", arrow = NULL, lineend = "butt", na.rm = FALSE, ...) {
+
+  GeomCurve$new(mapping = mapping, data = data, stat = stat,
+                position = position, arrow = arrow, lineend = lineend, na.rm = na.rm, ...)
+}
+
+GeomCurve <- proto(Geom, {
+  objname <- "curve"
+
+    draw <- function(., data, scales, coordinates, arrow = NULL,
+                     lineend = "butt", na.rm = FALSE, ...) {
+
+    data <- remove_missing(data, na.rm = na.rm,
+                           c("x", "y", "xend", "yend", "linetype", "size", "shape", "curvature", "angle", "ncp"),
+                           name = "geom_curve")
+
+    if (empty(data)) return(zeroGrob())
+
+    if (is.linear(coordinates)) {
+      return(with(coord_transform(coordinates, data, scales),
+                  curveGrob(x, y, xend, yend, default.units="native",
+                            curvature=curvature[1], angle=angle[1], ncp=ncp[1],
+                            square = FALSE, squareShape = 1,
+                            inflect = FALSE, open = TRUE,
+                            gp = gpar(col=alpha(colour, alpha), fill = alpha(colour, alpha),
+                                      lwd=size * .pt, lty=linetype, lineend = lineend),
+                            arrow = arrow)
+      ))
+    }
+    print("geom_curve is not implemented for non-linear coordinates")
+    return(zeroGrob())
+  }
+
+
+  default_stat <- function(.) StatIdentity
+  required_aes <- c("x", "y", "xend", "yend")
+  default_aes <- function(.) aes(colour="black", size=0.5, linetype=1, alpha = NA, curvature = 1, angle = 90, ncp = 1)
+  guide_geom <- function(.) "path"
+
+})

man/geom_curve.Rd

@@ -0,0 +1,61 @@
+% Generated by roxygen2 (4.1.1): do not edit by hand
+% Please edit documentation in R/geom-curve.r
+\name{geom_curve}
+\alias{geom_curve}
+\title{Single curved line segments.}
+\usage{
+geom_curve(mapping = NULL, data = NULL, stat = "identity",
+  position = "identity", arrow = NULL, lineend = "butt", na.rm = FALSE,
+  ...)
+}
+\arguments{
+\item{mapping}{The aesthetic mapping, usually constructed with
+\code{\link{aes}} or \code{\link{aes_string}}. Only needs to be set
+at the layer level if you are overriding the plot defaults.}
+
+\item{data}{A layer specific dataset - only needed if you want to override
+the plot defaults.}
+
+\item{stat}{The statistical transformation to use on the data for this
+layer.}
+
+\item{position}{The position adjustment to use for overlapping points
+on this layer}
+
+\item{arrow}{specification for arrow heads, as created by arrow()}
+
+\item{lineend}{Line end style (round, butt, square)}
+
+\item{na.rm}{If \code{FALSE} (the default), removes missing values with
+a warning.  If \code{TRUE} silently removes missing values.}
+
+\item{...}{other arguments passed on to \code{\link{layer}}. This can
+include aesthetics whose values you want to set, not map. See
+\code{\link{layer}} for more details.}
+
+\item{curvature}{see curveGrob}
+
+\item{angle}{see curveGrob}
+
+\item{ncp}{see curveGrob}
+}
+\description{
+Single curved line segments.
+}
+\section{Aesthetics}{
+
+\Sexpr[results=rd,stage=build]{ggplot2:::rd_aesthetics("geom", "curve")}
+}
+\examples{
+# Adding curve segments
+library(grid) # needed for arrow function
+b <- ggplot(mtcars, aes(wt, mpg)) + geom_point()
+b + geom_curve(aes(x = 2, y = 15, xend = 2, yend = 25, curvature = 0.2))
+b + geom_curve(aes(x = 2, y = 15, xend = 3, yend = 15, ncp = 2))
+b + geom_curve(aes(x = 5, y = 30, xend = 3.5, yend = 25), arrow = arrow(length = unit(0.5, "cm")))
+}
+\seealso{
+\code{\link{geom_segment}}, \code{\link{geom_path}} and \code{\link{geom_line}} for multi-
+segment lines and paths.
+}
+