Graphics Reference
In-Depth Information
Linked Views
Interactive operations are especially powerful if we link several statistical graphics at
the same time. It is usual to draw several graphics for one dataset to detect its char-
acteristics. A simple example is again a scatterplot matrix. If we highlight a group of
observations inone scatterplot component, it isusefultohighlight the same observa-
tions in other scatterplot components. his is an example of so-called “linked views”
or “linked highlighting” and “linked brushing.” A modern statistical graphics library
should support programming for linked views.
Advantages of Java
for Programming Statistical Graphics
17.2.2
Object-Oriented Programming Language
Java is an object-oriented programming (OOP) language: almost all things in Java
are written as objects (except primitive types). An object is a set of code and data.
As related code and data are encapsulated in an object, it is available as a component
for other programs. OOP is especially useful for realizing graphical user interfaces
and graphics programming, because components in these programs are easily im-
plemented by intuitive objects. For example, a point on a window is directly realized
by an object that has a location, size and color as data, and procedures for changing
values of these components as code.
Javaadopts aclass-instance mechanism,whereaclass isakind ofatypedefinition
and instances are realizations of classes. Classes have an inheritance mechanism that
is used for so-called “difference” programming. his means that a new class can be
defined by adding information to an existing class.
Platform Independence
ProgramswrittenintheJavalanguagerunsimilarlyonmanyplatforms.hisis
achieved through the Java virtual machine mechanism. Although this approach has
overheadforexecutingJavaprograms,recentJavavirtualmachineshavemechanisms
to reduce it.
his mechanism also permits the provision of standard libraries for accessing fea-
tures of host platforms, such as graphics, threading and networking, in unified ways.
Abundant Standard Libraries
As Java is not dependent on any specific platform, it provides a set of standard class
libraries that contain abundant common reusable functions for various modern op-
erating systems. hey support a wide range of tasks from basic ones such as network
access and file access to advanced tasks such as interactive GUI building. hey are
indispensable for statistical graphics programming.
It is important that standard libraries of Java are all written and controlled by the
original developer. It oten happened that many similar libraries were provided for
one language and users then found it di cult to choose between them. As Java has
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