Question

I’m trying to do what the title says. Obviously gnuplot is capable of doing this but I want to use JavaPlot to call it. The Graph3D class in JavaPlot makes me think its possible but as I have found no 3D examples and there’s almost no documentation on JavaPlot, I only have a rough idea how to go about this. If someone already knows how to do this and my efforts are going toward reinventing the wheel, please enlighten me, but for the moment I’ll proceed as if no one has tried to do this before.

Looking at the GNUPlot class, there’s a plot method, but the splot method is commented out and there’s no corresponding method in the GNUPlotExec class. I’ve tried to add one but currently it still plots in 2D. In the interest of full disclosure, I did not make this from scratch, but instead modified the current plot method.

This is the GNUPlot.class splot method that was commented out

    public void splot() throws GNUPlotException {
    exec.splot(param, term);
}

and this is the GNUPlotExec.class splot method derived from the plot method

void splot(GNUPlotParameters par, GNUPlotTerminal terminal) throws GNUPlotException {
    try {
        final GNUPlotTerminal term = terminal;  // Use this thread-aware variable instead of "terminal"
        final String comms = getCommands(par, term); // Get the commands to send to gnuplot
        final Messages msg = new Messages();    // Where to store messages from output threads

        /* Display plot commands to send to gnuplot */
        GNUPlot.getDebugger().msg("** Start of splot commands **", Debug.INFO);
        GNUPlot.getDebugger().msg(comms, Debug.INFO);
        GNUPlot.getDebugger().msg("** End of splot commands **", Debug.INFO);

        /* It's time now to start the actual gnuplot application */
        String[] command;
        if (ispersist) {
            command = persistcommand;
        } else {
            command = nopersist;
        }
        command[0] = getGNUPlotPath();
        {
            String cmdStr = "";
            for (String cmd : command) {
                cmdStr += cmd + " ";
            }
            GNUPlot.getDebugger().msg("exec(" + cmdStr + ")", Debug.INFO);
        }
        final Process proc = Runtime.getRuntime().exec(command);

        /* Windows buffers DEMAND asynchronus read & write */

        /* Thread to process the STDERR of gnuplot */
        Thread err_thread = new Thread() {

            public void run() {
                BufferedReader err = new BufferedReader(new InputStreamReader(proc.getErrorStream()));
                StringBuffer buf = new StringBuffer();
                String line;
                try {
                    while ((line = err.readLine()) != null) {
                        line = parseErrorLine(line, "gnuplot> splot");
                        line = line.replace("input data ('e' ends) >", "").trim();   // Remove entries having the "input data" prompt
                        if (line.equals("^")) {
                            line = "";
                        }  // Ignore line with error pointer
                        if (!line.equals("")) {     // Only take care of not empty lines
                            if (line.indexOf(GNUPlotParameters.ERRORTAG) >= 0) {
                                msg.error = "Error while parsing \'splot\' arguments.";    // Error was found in plot command
                                break;
                            }
                            buf.append(line).append('\n');
                        }
                    }
                    err.close();
                    msg.output = buf.toString(); // Store output stream
                } catch (IOException ex) {
                    ex.printStackTrace();
                }
            }
        };
        /* Thread to process the STDOUT of gnuplot */
        err_thread.start();
        Thread out_thread = new Thread() {

            public void run() {
                msg.process = term.processOutput(proc.getInputStream());    // Execute terminal specific output parsing
            }
        };
        out_thread.start();

        /* We utilize the current thread for gnuplot execution */
        OutputStreamWriter out = new OutputStreamWriter(proc.getOutputStream());
        out.write(comms);
        out.flush();
        out.close();


        try {
            proc.waitFor(); // wait for process to finish
            out_thread.join();  // wait for output (terminal related) thread to finish
            err_thread.join();  // wait for error (messages) output to finish
        } catch (InterruptedException ex) {
            throw new GNUPlotException("Interrupted execution of gnuplot");
        }

        /* Find the error message, if any, with precendence to the error thread */
        String message = null;
        if (msg.error != null) {
            message = msg.error;
        } else {
            message = msg.process;
        }

        /* Determine if error stream should be dumbed or not */
        int level = Debug.VERBOSE;
        if (message != null) {
            level = Debug.ERROR;
        }
        GNUPlot.getDebugger().msg("** Start of error stream **", level);
        GNUPlot.getDebugger().msg(msg.output, level);
        GNUPlot.getDebugger().msg("** End of error stream **", level);

        /* Throw an exception if an error occured */
        if (message != null) {
            throw new GNUPlotException(message);
        }

    } catch (IOException ex) {
        throw new GNUPlotException("IOException while executing \"" + getGNUPlotPath() + "\":" + ex.getLocalizedMessage());
    }

}

This is my test I’m trying to run

public static void main(String[] args) {

    GNUPlot p = new GNUPlot("path goes here");

    FunctionPlot myPlot = new FunctionPlot("tan(x)");

    p.addPlot(myPlot);

    p.splot();
}

I believe the commands that are getting executed by gnuplot are

gnuplot> _gnuplot_error = 1
gnuplot> plot tan(x) title 'tan(x)' ; _gnuplot_error = 0
gnuplot> if (_gnuplot_error == 1) print '_ERROR_'
gnuplot>          undefined function: if

and of course that should say splot, not plot

Answer 1

Figured it out. I needed to add

p.new3DGraph();

in main before p.addPlot(myPlot);
Hopefully this will help someone else cause man, there is nothing on JavaPlot out there