Add function poly.gui(), a gWidgets function to teach polynomial regression.

DESCRIPTION

@@ -15,8 +15,8 @@ Imports:
     latticeExtra
 Suggests:
     plyr,
-    rpanel,
-    gWidgets
+    gWidgets,
+    gWidgetstcltk
 License: GPL-3 | file LICENSE
 URL: http://git.leg.ufpr.br/leg/legTools
 BugReports: http://git.leg.ufpr.br/leg/legTools/issues

NAMESPACE

 # Generated by roxygen2 (4.1.1): do not edit by hand
 
+export(poly.gui)
 export(subsetDropAll)

R/poly.gui.R

+#' @title Polynomial regression GUI
+#' 
+#' @name poly.gui
+#'
+#' @description This function opens a interface to control the
+#' polynomial degree in linear regression. It shows the observed values
+#' and the corresponding fitted curve superimposed with confidence bands
+#' (for the fitted value) and show the residuals plot too. It assumes
+#' that \code{gWidgets} and \code{gWidgetstcltk} packages are available.
+#'
+#' @param x,y independent and dependent (numeric) regression variables.
+#' 
+#' @param data an optional \code{data.frame}.
+#'
+#' @param er stands for extend range. It is used to extend the plotting
+#' range by a fraction on both sides and directions. Default is
+#' 0.05. See \link[grDevices]{extendrange}.
+#'
+#' @return None is returned by the function.
+#'
+#' @export
+#' @examples
+#' \donttest{
+#' 
+#' poly.gui(x=area, y=peri, data=rock, er=0.3)
+#' poly.gui(x=speed, y=dist, data=cars, er=0.3)
+#' poly.gui(x=eruptions, y=waiting, data=faithful, er=0.3)
+#' 
+#' }
+poly.gui <- function(x, y, data, er=0.05){
+    ##
+    ##-------------------------------------------
+    ## Loading the required packages.
+    ## 
+    if (!requireNamespace("gWidgets", quietly=TRUE)){
+        stop("`gWidgets` needed for this function to work. Please install it.",
+             call.=FALSE)
+    }
+    if (!requireNamespace("gWidgetstcltk", quietly=TRUE)){
+        stop("`gWidgetstcltk` needed for this function to work. Please install it.",
+             call.=FALSE)
+    }
+    stopifnot(require(gWidgets))
+    stopifnot(require(gWidgetstcltk))
+    options(guiToolkit="tcltk")
+    ##
+    ##-------------------------------------------
+    ## Functions to annotate in the plot upper margin.
+    ## 
+    annotations <- function(lm.obj){
+        mtext(side=3, adj=0, line=1.5,
+              text=sprintf("X rank: %i", lm.obj$rank))
+        mtext(side=3, adj=0, line=0.5,
+              text=sprintf("Residual DF: %i", lm.obj$df.residual))
+        press <- sum((residuals(lm.obj)/(1-hatvalues(lm.obj)))^2)
+        mtext(side=3, adj=1, line=0.5,
+              text=sprintf("PRESS: %0.2f", press))
+        sm <- summary(lm.obj)
+        lastcoef <- sprintf("High term p-value: %0.5f",
+                            sm$coeff[length(coef(lm.obj)), 4])
+        mtext(side=3, adj=1, line=2.5, text=lastcoef)
+        mtext(side=3, adj=1, line=1.5,
+              text=sprintf("R² (adj. R²): %0.2f (%0.2f)",
+                  100*sm$r.squared, 100*sm$adj.r.squared))
+    }
+    ##
+    ##-------------------------------------------
+    ## Auxiliary variables not controled by the GUI.
+    ##
+    xlab <- deparse(substitute(x))
+    ylab <- deparse(substitute(y))
+    if(!missing(data)){
+        da <- eval(data, envir=parent.frame())
+        x <- da[, deparse(substitute(x))]
+        y <- da[, deparse(substitute(y))]
+    }
+    maxd <- as.integer(length(unique(x))-1)
+    xr <- extendrange(x, f=er)
+    yr <- extendrange(y, f=er)
+    newdata <- data.frame(x=seq(xr[1], xr[2], length.out=200))
+    ##
+    ##-------------------------------------------
+    ## Function controled by the GUI.
+    ## 
+    draw.poly <- function(h, ...){
+        svalue(degree) <- min(c(
+            max(c(1L, svalue(degree)+h$action$val)),
+            maxd))
+        m0 <- lm(y~poly(x, degree=svalue(degree)))
+        switch(svalue(plottype),
+               "Scatter plot"={
+                   cb <- predict(m0, newdata=newdata, interval="confidence")
+                   plot(y~x, xlim=xr, ylim=yr,
+                        xlab=xlab, ylab=ylab)
+                   matlines(newdata$x, cb, lty=c(1,2,2), col=1)
+                   annotations(m0)
+               },
+               "Residuals"={
+                   par(mfrow=c(2,2))
+                   plot(m0)
+                   layout(1)
+               })
+    }
+    ##
+    ##-------------------------------------------
+    ## Building the GUI.
+    ## 
+    w <- gwindow(title="Polynomial regression", visible=FALSE)
+    g <- ggroup(container=w, horizontal=FALSE)
+    gg_label <- ggroup(container=g)
+    dlabel <- glabel(text="Polynomial degree:",
+                     container=gg_label)
+    degree <- gedit(text=1, width=2, coerce.with=as.integer,
+                    handler=draw.poly, action=list(val=0L),
+                    container=gg_label)
+    gg_buttons <- ggroup(container=g)
+    gminus <- gbutton(text="-",
+                      handler=draw.poly,
+                      action=list(val=-1L),
+                      container=gg_buttons)
+    gplus <- gbutton(text="+",
+                     handler=draw.poly,
+                     action=list(val=1L),
+                     container=gg_buttons)
+    gg_radio <- ggroup(container=g)
+    plottype <- gradio(items=c("Scatter plot", "Residuals"),
+                       horizontal=TRUE,
+                       handler=draw.poly,
+                       action=list(val=0L),
+                       container=gg_radio)
+    do.call(what=draw.poly, args=list(h=list(degree=1L)))
+    visible(w) <- TRUE
+    invisible()
+}

man/poly.gui.Rd

+% Generated by roxygen2 (4.1.1): do not edit by hand
+% Please edit documentation in R/poly.gui.R
+\name{poly.gui}
+\alias{poly.gui}
+\title{Polynomial regression GUI}
+\usage{
+poly.gui(x, y, data, er = 0.05)
+}
+\arguments{
+\item{x,y}{independent and dependent (numeric) regression variables.}
+
+\item{data}{an optional \code{data.frame}.}
+
+\item{er}{stands for extend range. It is used to extend the plotting
+range by a fraction on both sides and directions. Default is
+0.05. See \link[grDevices]{extendrange}.}
+}
+\value{
+None is returned by the function.
+}
+\description{
+This function opens a interface to control the
+polynomial degree in linear regression. It shows the observed values
+and the corresponding fitted curve superimposed with confidence bands
+(for the fitted value) and show the residuals plot too. It assumes
+that \code{gWidgets} and \code{gWidgetstcltk} packages are available.
+}
+\examples{
+\donttest{
+
+poly.gui(x=area, y=peri, data=rock, er=0.3)
+poly.gui(x=speed, y=dist, data=cars, er=0.3)
+poly.gui(x=eruptions, y=waiting, data=faithful, er=0.3)
+
+}
+}
+