2: Simple example
4: Finer Control
5: X-Y Plots
6: Contour Plots
7: Image Plots
9: Gri Commands
12: Emacs Mode
15: Gri Bugs
16: Test Suite
17: Gri in Press
1: IntroductionGri is a programming language for drawing science-style graphs. It is not mouse-driven, and it does not draw business-style graphs (e.g. pie charts, three-dimensional graphs). Gri has substantial power in advanced applications. It has been proven to be easy to learn; for simple applications, the learning curve is less than an hour. Many users regard Gri as the plotting equivalent of the LaTeX document preparation system.
Computers Gri works on: unix computers of many types, plus Microsoft Windows, and Macintosh OSX. You'll find Gri pre-packaged for various unixes, e.g. linux/debian, linux/redhat, and freeBSD.
Capabilities of Gri are those scientists commonly want, since Gri was written by a scientist. It is not so useful for business people -- e.g., Gri draws xy graphs (see X-y Plots), contour plots (see Contour Plots), and image plots (see Images), but it will not draw pie-charts unless you teach it how. The list of capabilities of Gri is similar to many packages, but unlike many of the other packages, Gri gives you control over line widths, fonts, grayscales, etc. (see Getting More Control), and it is a programming language of moderate power.
The Gri drawing metaphor is that of pen on paper. The ink in the
pen is opaque. An item drawn in white ink will erase a previously drawn
underlying object drawn in black ink. For example, to draw a timeseries
curve in which the region between positive data values and the y=0 axis
is filled with black ink, you might use (`
Input/output in Gri may be interactive or non-interactive. For
interactive use, type `
Gri output is in the PostScript page description language. The output is therefore of high quality, device-independent, capable of being inserted into popular text processors (e.g. LaTeX), and easily displayed.
Online help: the Gri command `
Data analysis in Gri is limited. It has rudimentary data analysis functions, such as regression, column manipulation, smoothing, etc, but it is not intended as an integrated analysis/graphics package.
System calls are an easy and important facet of Gri. It is easy to use operating system commands within Gri (see System; see Operating System; see Get Env). This allows you to use familiar, powerful tools, and keeps Gri simple. Particularly useful is the ability to read files through operating system filters (see Open).
Programming Gri is quite straightforward, and users familiar with
other programming languages find it easy. If Gri lacks a drawing
method, you can add it fairly easily, since Gri has programming elements
such as `
Version Numbering Scheme
When you launch Gri interactively (without naming a commandfile, i.e. by
just typing `
The last line is a prompt, suggesting that you type in Gri commands.
You may type `
The first line gives the version number. You can also get this by
running Gri with the command `