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// -*- mode: C++; c-indent-level: 4; c-basic-offset: 4; tab-width: 8; -*-
//
// Wt usage example for RInside, inspired by the standard 'density sliders' example
//
// Copyright (C) 2011 Dirk Eddelbuettel and Romain Francois
//
// This file is licensed under GPL 2 or later, as are the rest of RInside and Rcpp
//
// Derived from hello.C in the Wt sources
// Copyright (C) 2008 Emweb bvba, Heverlee, Belgium.
#include <cstdio>
#include <Wt/WApplication>
#include <Wt/WBreak>
#include <Wt/WContainerWidget>
#include <Wt/WLineEdit>
#include <Wt/WPushButton>
#include <Wt/WText>
#include <Wt/WImage>
#include <Wt/WSpinBox>
#include <Wt/WGroupBox>
#include <Wt/WButtonGroup>
#include <Wt/WRadioButton>
#include <Wt/WHBoxLayout>
#include <Wt/WEnvironment>
#include <Wt/WFileResource>
#include <RInside.h>
using namespace Wt;
class DensityApp : public WApplication {
public:
DensityApp(const WEnvironment& env, RInside & R);
private:
WLineEdit *codeEdit_; // to edit the RNG draw expression
WButtonGroup *group_; // holds the radiobuttons
WSpinBox *spin_; // selects the density bandwidth
WImage *img_; // displays the image
WFileResource *imgfile_; // controls the file resources
WText *greeting_; // text label for status message
void reportButton(); // called when new button selected
void reportEdit(); // called when RNG expression edited
void reportSpinner(); // called when bandwidth changed
void plot(); // to call R for new plot
enum Kernel { Gaussian = 0, Epanechnikov = 1, Rectangular = 2,
Triangular = 3, Cosine = 4 };
RInside & R_; // reference to embedded R instance
std::string tempfile_; // name of file used by R for plots
int bw_, kernel_; // parameters used to estimate the density
std::string cmd_; // random draw command string
Rcpp::NumericVector Yvec_; // the random draw
};
// The env argument contains information about the new session, and the initial request.
// It must be passed to the WApplication // constructor so it is typically also an argument
// for your custom application constructor.
DensityApp::DensityApp(const WEnvironment& env, RInside & R) : WApplication(env), R_(R) {
setTitle("Witty WebApp With RInside"); // application title
std::string tfcmd = "tfile <- tempfile(pattern=\"img\", tmpdir=\"/tmp\", fileext=\".png\")";
tempfile_ = Rcpp::as<std::string>(R_.parseEval(tfcmd)); // assign to 'tfile' in R, and report back
bw_ = 100;
kernel_ = 0; // parameters used to estimate the density
cmd_ = "c(rnorm(100,0,1), rnorm(50,5,1))"; // random draw command string
Wt::WGroupBox *wc = new Wt::WGroupBox("Density Estimation", root());
Wt::WHBoxLayout *layout = new Wt::WHBoxLayout();
Wt::WContainerWidget *midbox = new Wt::WContainerWidget(root());
layout->addWidget(midbox);
Wt::WContainerWidget *container = new Wt::WContainerWidget(root());
layout->addWidget(container);
wc->setLayout(layout, AlignTop | AlignJustify);
midbox->addWidget(new WText("Density estimation scale factor (div. by 100)"));
midbox->addWidget(new WBreak()); // insert a line break
spin_ = new WSpinBox(midbox);
spin_->setRange(5, 200);
spin_->setValue(bw_);
spin_->valueChanged().connect(this, &DensityApp::reportSpinner);
midbox->addWidget(new WBreak()); // insert a line break
midbox->addWidget(new WText("R Command for data generation")); // show some text
midbox->addWidget(new WBreak()); // insert a line break
codeEdit_ = new WLineEdit(midbox); // allow text input
codeEdit_->setTextSize(30);
codeEdit_->setText(cmd_);
codeEdit_->setFocus(); // give focus
codeEdit_->enterPressed().connect(this, &DensityApp::reportEdit);
group_ = new Wt::WButtonGroup(container); // use button group to arrange radio buttons
Wt::WRadioButton *button;
button = new Wt::WRadioButton("Gaussian", container);
new Wt::WBreak(container);
group_->addButton(button, Gaussian);
button = new Wt::WRadioButton("Epanechnikov", container);
new Wt::WBreak(container);
group_->addButton(button, Epanechnikov);
button = new Wt::WRadioButton("Rectangular", container);
new Wt::WBreak(container);
group_->addButton(button, Rectangular);
button = new Wt::WRadioButton("Triangular", container);
new Wt::WBreak(container);
group_->addButton(button, Triangular);
button = new Wt::WRadioButton("Cosine", container);
new Wt::WBreak(container);
group_->addButton(button, Cosine);
group_->setCheckedButton(group_->button(kernel_));
group_->checkedChanged().connect(this, &DensityApp::reportButton);
Wt::WGroupBox *botbox = new Wt::WGroupBox("Resulting chart", root());
imgfile_ = new Wt::WFileResource("image/png", tempfile_);
imgfile_->suggestFileName("density.png"); // name the clients sees of datafile
img_ = new Wt::WImage(imgfile_, "PNG version", botbox);
Wt::WGroupBox *stbox = new Wt::WGroupBox("Status", root());
greeting_ = new WText(stbox); // empty text
greeting_->setText("Setting up...");
reportEdit(); // create a new RNG draw in Yvec_
plot(); // and draw a new density plot
}
void DensityApp::reportButton() {
kernel_ = group_->checkedId(); // get id of selected kernel
plot();
}
void DensityApp::reportEdit() {
cmd_ = codeEdit_->text().toUTF8(); // get text written in box, as UTF-8, assigned to string
std::string rng = "y <- " + cmd_ + ";";
R_.parseEvalQ(rng); // evaluates expression, assigns to 'y'
Yvec_ = R_["y"]; // cache the y vector
plot();
}
void DensityApp::reportSpinner() {
bw_ = spin_->value(); // get the value of the spin selector
plot();
}
void DensityApp::plot() {
const char *kernelstr[] = { "gaussian", "epanechnikov", "rectangular", "triangular", "cosine" };
greeting_->setText("Starting R call");
R_["tfile"] = tempfile_;
R_["bw"] = bw_;
R_["kernel"] = kernelstr[kernel_]; // passes the string to R
R_["y"] = Yvec_;
std::string cmd0 = "png(filename=tfile,width=600,height=400); plot(density(y, bw=bw/100, kernel=kernel), xlim=range(y)+c(-2,2), main=\"Kernel: ";
std::string cmd1 = "\"); points(y, rep(0, length(y)), pch=16, col=rgb(0,0,0,1/4)); dev.off()";
std::string cmd = cmd0 + kernelstr[kernel_] + cmd1; // stick the selected kernel in the middle
R_.parseEvalQ(cmd); // evaluate command -- generates new density plot
imgfile_->setChanged(); // important: tells consumer that image has changed, forces refresh
greeting_->setText("Finished request from " + this->environment().clientAddress() + " using " + this->environment().userAgent()) ;
}
WApplication *createApplication(const WEnvironment& env) {
// You could read information from the environment to decide whether
// the user has permission to start a new application
//
// We grab an instance of the embedded R. Note we can start only one,
// so resource conflicts have to be managed (eg add mutexes etc)
//
return new DensityApp(env, RInside::instance());
}
int main(int argc, char **argv) {
RInside R(argc, argv); // create the one embedded R instance
// Your main method may set up some shared resources, but should then
// start the server application (FastCGI or httpd) that starts listening
// for requests, and handles all of the application life cycles.
//
// The last argument to WRun specifies the function that will instantiate
// new application objects. That function is executed when a new user surfs
// to the Wt application, and after the library has negotiated browser
// support. The function should return a newly instantiated application
// object.
return WRun(argc, argv, createApplication);
}
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