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22 free tools for data visualization and analysis

April 20, 2011 06:00 AM ET


Update: Protovis is no longer being developed, and the team is now working on the D3 JavaScript library. See our writeup of D3 (March 6, 2013).

What it does: Billed as a "graphical toolkit for visualization," this project from Stanford University's Visualization Group is one of the more popular JavaScript libraries for turning data into visuals; it's designed to balance simplicity with control over the display.

What's cool: One of the best things about Protovis is how well it's documented, with plenty of examples featuring visualization and sample code. There are also a large number of sample visualization types available, including maps and some statistical analyses. This is a robust tool, capable of building graphics like this color-coded U.S. map with timeline slider.

Drawbacks: As is the case with other JavaScript libraries, it's pretty much essential for users to have knowledge of JavaScript (or at least some other programming language). While it's possible to copy, paste and modify code without really understanding what it's doing, I find it difficult to recommend that approach for nontechnical end users.

Skill level: Expert.

Runs on: JavaScript-enabled Web browsers.

Learn more: Try the How-to: Get Started Guide. You can also find examples of the types of graphics you can build with Protovis at the Protovis Gallery.

GIS/mapping on the desktop

There's a wide range of business uses for geographic information systems (GIS), ranging from oil exploration to choosing sites for new retail stores. Or, as The Miami Herald did for its Pulitzer Prize-winning coverage of Hurricane Andrew, you can compare maximum wind speeds with damage reports and building information (and perhaps discover, for example, that the worst damage didn't happen in the areas suffering the heaviest winds, but in areas with a lot of new, shoddy construction).

Quantum GIS (QGIS)

What it does: This is full-fledged GIS software, designed for creating maps that offer sophisticated, detailed data-based analysis of a geographic regions.

The best-known desktop GIS software is probably Esri's ArcView, a robust, well-supported application that costs quite a bit of money. The open-source QGIS is an alternative to ArcView.

Free data analysis
Quantum GIS (QGIS) offers full-fledged geospatial visualization and analysis on the desktop.
Click to view larger image.

As OpenOffice is to Microsoft Office, QGIS is to ArcView. ArcView enthusiasts argue that Esri's offering is a couple of years ahead of open-source alternatives, has a better-developed interface, enjoys commercial support and is better suited for print output. But QGIS users say the open-source alternative is an excellent program that does a great deal of useful GIS work -- and may even be better than ArcView when it comes to generating maps for the Web, thanks to a plug-in dedicated to generating HTML image maps.

What's cool: QGIS has an enormous amount of GIS functionality, including the ability to create maps, overlay various types of data, do spatial analysis, publish to the Web and more. It can also be enhanced with plug-ins that add support for numerous undertakings, including geocoding, managing underlying table data, exporting to MySQL and generating HTML image maps.

Drawbacks: As with any sophisticated GIS application, learning to use this software entails a serious commitment of time and training. Even in hour-long hands-on sessions with first ArcView and then QGIS, I noticed things that were easier to do in the commercial option. For example, ArcView had a one-click "normalize" function to immediately calculate, say, the percentage of people 65 and over versus the total population from a data table with both columns; in QGIS, I needed to pull up a "field calculator" and create a new column with the formula to do that calculation myself.

Runs on: Linux, Unix, Mac OS X, Windows. (This is one case where installation is more complicated on OS X, since it requires manual installation of several dependencies. There's a one-click installer for Windows.)

Skill level: Intermediate to expert.

Learn more: Timothy Barmann of The Providence Journal posted two very useful tutorials for the CAR conference that are still available: Introduction to QGIS and The Latest in Mapping With JavaScript and jQuery. Barmann also offers a sample: Rhode Island's Ethnic Mosaic. Another resource to help you get started: QGIS Tutorial Labs from Richard E. Plant, professor emeritus at the University of California, Davis.

Note: If you're interested in GIS and want to consider other free software options, download this PDF listing of Open Source/Non-Commercial GIS Products. And if you're looking for a free open-source desktop GIS program that might be fairly easy to use, Jacob Fenton, director of computer-assisted reporting at American University's Investigative Reporting Workshop, recommends taking a look at the System for Automated Geoscientific Analyses (SAGA) site. Finally, if analyzing geographic data in a conventional database sounds interesting, PostGIS "spatially enables" the PostgreSQL relational database, according to the site.

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