Ptplot 5.8 - Java Plotter

Authors Edward A. Lee Christopher Brooks Contributors Lukito Muliadi William Wu Jun Wu

• Embeddable in applets or applications.
• Auto-ranging.
• Automatic or manual labeling of axes.
• Automatic or manual tick marks.
• Logarithmic axes.
• Live, animated plots.
• Infinite zooming.
• Various plot styles: connected lines, scatter plot, bars, etc.
• Various point styles: none, dots, points, and unique marks.
• Multiple data sets and a legend.
• Color or black and white plotting.
• Error bars.
• Editable plots.
• PlotML, and XML language for specifying plots.
• Compatibility with pxgraph, an older plotting program.

There is a set of demonstrations of the various capabilities. There are several ways to use the classes in the plot package.

• You can invoke an executable, ptplot, which is a shell script, to plot data on the local file system or on the network.
• You can invoke an executable, pxgraph, which is a shell script, to plot data that is stored in binary format compatible with the older program pxgraph.
• You can invoke a Java application, such as PlotMLApplication, by setting your CLASSPATH variable appropriately and using the java executable that is included in your Java distribution.
• You can reference an existing applet class, such as PlotMLApplet, in an HTML file. The applet parameters, such as dataurl, give the plot data and format information, either by referring to another file on the network, or by directly including the information. You do not even have to have Ptplot installed on your server, since you can always reference the Berkeley installation.
• You can create new classes derived from applet, frame, or application classes to customize your plots. This allows you to completely control the placement of plots on the screen, and to write Java code that defines the data to be plotted.

The plot data can be specified in any of three data formats:

• PlotML is an XML extension for plot data. Its syntax is similar to that of HTML.
• An older, simpler syntax for plot data is also provided, although in the long term, that syntax is unlikely to be maintained (it will not necessarily be expanded to include new features). For simple data plots, however, it is adequate. Using it for applets has the advantage of making it possible to reference a slightly smaller jar file containing the code, which makes for more responsive applets.
• A binary file format used by the popular pxgraph program, an extension of xgraph, is supported by classes in the compat package. There is also a shell script, called pxgraph, which invokes these classes. Formatting information in pxgraph (and in the compat package) is provided by command-line arguments, rather than being included with the plot data, exactly as in the older program. Applets specify these command-line arguments as an applet parameter.

The above classes define panels that are used by placing them into a user interface context such as an applet or the top-level window of an application. A number of classes are provided to support common situations, but you should keep in mind that these classes are by no means comprehensive. Many interesting uses of the plot package involve writing Java code to create customized user interfaces that include one or more plots. The most commonly used built-in classes are those in the plotml package, which can read PlotML files and the older textual syntax. These classes are include:

• PlotMLApplet: A simple applet that can read PlotML files off the web and render them.
• EditablePlotMLApplet: A version that allows editing of any data set in the plot.
• PlotMLFrame: A top-level window containing a plot defined by a PlotML file.
• PlotMLApplication: An application that can be invoked from the command line and reads PlotML files.
• EditablePlotMLApplication: An extension that allows editing of any data set in the plot.

The last of these is the class invoked by the ptplot command-line script. It can open plot files, edit them, print them, and save them. There are simpler version of some of these in the plot package that cannot read PlotML files, but can read an older, simpler syntax. The only reason to use these simpler versions is for the slightly smaller jar file sizes, which can improve the responsivity of applets.

TwoPlotExample is a very simple sample Ptplot application that uses only core classes in the plot package, and exercises complete control over the layout of the page.

Backward compatibility with the C pxgraph program is provided in the compat package by the PxgraphApplet and PxgraphApplication classes in the compat package.

This code owes a heavy debt to David Harrison, the original author of xgraph, which runs under the X window system on Unix platforms. An extension to xgraph called pxgraph, written by Joe Buck, reads binary files as well as ASCII. For compatibility with these programs, we have provided a Bourne Shell script called pxgraph that is a drop-in replacement for either xgraph or pxgraph. Unlike the original program, however, the Java implementation does not depend on the X window system. We have provided a DOS batch file called pxgraph.bat that brings pxgraph capability to Windows platforms.

Last Updated: $Date: 2010-10-05 18:29:54 -0700 (Tue, 05 Oct 2010) $