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22 free tools for data visualization and analysis

Sharon Machlis | Jan. 3, 2012
There are many tools around to help turn data into graphics, but they can carry hefty price tags.

And while the fact that DataWrangler is a Web-based service makes it convenient to use, don't forget that it sends your data off to an external site -- which means it isn't an option for sensitive internal information. However, there are plans for a future release of a stand-alone desktop version. Another important thing to keep in mind is that DataWrangler is currently alpha code, and its creators say it's "still a work in progress."

Skill level: Advanced beginner.

Runs on: Any Web browser.

Learn more: There's a screencast on the Data Wrangler home page. Also, see this post on using DataWrangler to format data (from Tableau Public's blog).

Google Refine

What it does: Google Refine can be described as a spreadsheet on steroids for taking a first look at both text and numerical data. Like Excel, it can import and export data in a number of formats including tab- and comma-separate text files and Excel, XML and JSON files.

Refine features several built-in algorithms that find text items that are spelled differently but actually should be grouped together. After importing your data, you simply select edit cells --> cluster and edit and select which algorithm you want to use. After Refine runs, you decide whether to accept or reject each suggestion. For example, you could say yes to combining Microsoft and Microsoft Corp., but no to combining Coach Inc. with CQG Inc. If it's offering too few or too many suggestions, you can change the strength of the suggestion function.

There are also numerical options that offer quick and easy overviews of data distributions. This functionality can reveal anomalies that might be the result of data input errors -- such as $800,000 instead of $80,000 for a salary entry, or it could expose inconsistencies -- such as differences in the way compensation data is reported from entry to entry, with some showing, say, hourly wages and others showing weekly pay or yearly salaries.

Beyond data housekeeping, Google Refine offers some useful analysis tools, such as sorting and filtering.

What's cool: Once you get used to which commands do what, this is a powerful tool for data manipulation and analysis that strikes a good balance between functionality and ease of use. The undo/redo list of every action you've taken lets you roll back when needed. And text functions handle Java-syntax regular expressions, allowing you to look for patterns (such as, say, three numbers followed by two digits) as well as specific text strings and numbers.

Finally, while this is a browser-based application, it works with files on your desktop, so your data remains local.

 

 

Drawbacks: Although Google Refine looks like a spreadsheet, you can't do typical spreadsheet calculations with it; for that, you must export to a conventional spreadsheet application. If you've got a large data set, carve out some time in your day to go through all of Refine's suggested changes, since it can take a while. And, depending on the data set, be prepared when looking for text items to merge: You're likely to get either a lot of false positives or missed problems -- or both.

 

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