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computer science

GGobi

GGobi is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand GGobi rather than just read about it. In short: GGobi is a free statistical software tool for interactive data visualization. GGobi allows extensive exploration of the data with Interactive dynamic graphics.

GGobi — main illustration
GGobi — illustration

Key takeaways

  • GGobi belongs to computer science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect GGobi to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of GGobi from memory before moving on to harder problems.

Reference excerpt

GGobi is a free statistical software tool for interactive data visualization. GGobi allows extensive exploration of the data with Interactive dynamic graphics. It is also a tool for looking at multivariate data. R can be used in sync with GGobi (through rggobi). The GGobi software can be embedded as a library in other programs and program packages using an application programming interface (API) (integration into a stand-alone application) or as an add-on to existing languages and scripting environments, e.g., with the R command line or from a Perl or Python scripts. GGobi prides itself on its ability to link multiple graphs together.

Overview GGobi was created to look at data matrices. The designers were interested in exploring multi-dimensional data. The program developers went through many name changes before settling on GGobi (A combination of the words GTK+ and the Gobi Desert). The original concept, Dataviewer, began in the mid-80s, and a predecessor, XGobi, began in 1989. Work began on the current version of GGobi in 1999. The main reason for the different versions was the change in technology. Current version for MS Windows is 2.1.10a (12 March 2010) with an update for 64 bit usage from 10 June 2012. Released under a combination of three free software licenses, GGobi is free software.

GGobi Topics

Importance of graphics Looking at data through various graphs can reveal more information about the distribution than just looking at the numbers or a summary of them. Using the different tools within GGobi, clusters, non-linear distributions, outliers, and other important variations in the data can be discovered. GGobi is a program which allows exploratory data analysis to occur for multi-dimensional data.

Supported data sources GGobi can read CSV and XML file types.

Types of graphics 1D: Average shifted histogram, textured dot plot, barchart, spineplot 2D: Scatterplot High-D: Scatterplot matrix Parallel coordinates Grand tour, projection pursuit guided tour, manual tour Time series plot

Interactions These tools can be used to pick out special points or clusters of data.

Brushing As the brush moves over a point, the point will be highlighted. If "persistent" is selected, the points the brush has moved over will remain "painted". Identify As the cursor moves over a point, a label, or variable value will appear at the top of the graphic screen. Linking Multiple plots are linked so identifying one point in one plot will identify the same point on all other graphs, and brushing a group of points in one plot will highlight the same points in other plots. The linking can be one-to-one, or according to the values of a categorical variable in the data set. Moving points Points in a plot can be moved interactively, e.g. to gauge results from multidimensional scaling. Add/remove points or edges.

See also

Data visualization Mondrian data analysis

References

Further reading Buja, A., D. Cook, and D.F. Swayne (March 1998). "XGobi: Interactive Dynamic Data Visualization in the X Window System". in: Journal of Computational and Graphical Statistics 7 (1): 113–130. Buja, A., D.T. Lang, and D.F. Swayne (August 28, 2003). "GGobi: Evolving From XGobi into an Extensible Framework for Interactive Data Visualization". In: Journal of Computational Statistics and Data Analysis 43 (4): 423–444. Cook, D. and D.F. Swayne (2007), with contributions from Andreas Buja, Duncan Temple Lang, Heike Hofmann, Hadley Wickham, and Michael Lawrence. Interactive and Dynamic Graphics for Data Analysis: With R and GGobi. DOI: 10.1007/978-0-387-71762-3, Springer-Verlag New York.

External links GGobi Data Visualization System rggobi is an R package that interfaces R and GGobi. GGobi blog References to GGobi on the web include links at Humboldt University [1] Archived 2008-04-10 at the Wayback Machine, Ubuntu [2], Debian [3], Freshmeat [4], Hugh-Public [5], Softpedia [6].

Illustrations

GGobi: Parallel coordinate plot linked to scatterplot, show traces of the two points highlighted in the scatterplot
Parallel coordinate plot linked to scatterplot, show traces of the two points highlighted in the scatterplot

Worked examples

Example 1 — a first encounter with GGobi

Start with the simplest possible case. Write down what GGobi claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to GGobi before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about GGobi ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of GGobi

In research
GGobi appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses GGobi in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
GGobi is common in secondary-school and first-year university syllabi. It links to neighbouring topics Free plotting software, Free statistical software, so understanding it makes those chapters shorter.
In everyday life
Look for GGobi outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study GGobi in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what GGobi means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain GGobi out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is GGobi in simple terms?

GGobi is a free statistical software tool for interactive data visualization. GGobi allows extensive exploration of the data with Interactive dynamic graphics.

Why does GGobi matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study GGobi?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on GGobi.

Tags

  • Free plotting software
  • Free statistical software

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