Ravelation Using Ravel Developers Examples Buy Ravel Support

Please see Ravel for Excel for the Excel Ravel Addin.

You have already met the basic Ravel OLAP operations for pivoting, rollup, drilldown and slicing.

More advanced Ravel features need to be enabled by external menus or other controls, which may or may not be available in your application.

Rank

The dimensionality of the data output by a Ravel is called it's rank. Typically, this might be 1, for controlling a line plot or bar chart, or 2D for controlling a spreadsheet or surface plot, but higher ranks are possible as well.

Reductions

We already met the operation of summing along an axis in the introduction. In fact a range of reduction operations can be applied, include product, minimum, maximum, average and standard deviation.

Sorting

The labels along each axis may be sorted lexicographically (like alphabetical order, but for all ASCII characters, not just `A' to `Z'), in either forward or reverse directions. If sorting is none, then the labels will have the original order they appear in the dataset.

Labels may also be sorted numerically. To understand the difference between lexicographic and numerical sorting order, you need to understand that ``2'' is lexicographically bigger than ``199'', but numerically less.

The final sorting option that may be available is sorting by value. For rank 1 ravels, data is output in increasing or decreasing value, with the axis labels appropriatly reordered. For rank 2 ravels, you need to specify a row or column along which the values are used to determine sorting order. For higher rank ravels, you need to specify a rank-1 dimensional slice to determine the sorting order. A rank 1 ravel may be used as a suitable input widget to determine the value sorting.

Calipers/Filtering

You can restrict the range of data output along a particular axis by enabling calipers on that axis that control the minimum and maximum label along that axis. This is sometimes known as dicing in the OLAP world. By working together with sorting options, you can control which labels are filtered in.

Filter by value

Another filtering option is to specify a range of values to restrict the output to. If this is an option, you can enable a box whisker control allowing you to adjust the output values.



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