# Ring Plots

Ring plots present the numeric values of categorical data as segments of circular rings. Sequential data values are considered to belong to different categories and are plotted with distinct patterns. The data values from different series are assigned to these categories based on the position of the value in the series, for example, the second data value taken from each series all share one category. The data values are used to determine the size of the arc based on the proportionate size of the data value to the sum of all data values in the series. For example, if the series had values { 1.12, 4.48, 3.36, 1.68, 0.56}, the contribution of each ring section to the total would be {0.10, 0.40, 0.330, 0.15, 0.0 5}, since 0.10= 1.12/(1.12+4.48+3.36+1.68+0.56), and the angular arcs of the sections would be {36, 144, 108, 54, 18} degrees, since 36=0.10*360.

Ring plots do not have any sub-types.

Ring plot styles provide two choices. Ring plots can be plotted with all segments linked into a single overall ring, with different series plotted immediately adjacent to one another in sequentially larger rings. Alternatively, the segments of the outermost ring can be split and float a certain distance away from the next ring.

Figure 10-11An example of ring plots

This screenshot shows a table of data and two ring plots. The data consist of a single data series organized in a row and starting with the word "Widgets". The data consist of three series organized by row and starting with the words "Widgets", "Gadgets", and "Lumpets". Each of these series has values in five categories. The two graphs illustrate the two sub-types of ring plots, the left most plot without any gaps and the right most plot having the outer plot with gaps.

Each series in ring plots can include three main elements and two error elements, although only the value element is necessary. The series can have a 'Name' element, which is a single text entry used to identify the series, must have a 'Values' element, which is a sequence of numeric values, and may have a 'Label' element, which is a sequence of text entries used to identify the categories. All of these elements can be defined as references to a region of the worksheet, as literally defined entries, or as formula expressions which result in the correct type. The 'Label' element is shared by all of the series. The legend added to a ring plot identifies the different series, by default using the entries of the 'Name' element of each series. The two error elements include a list for errors in the positive direction and one for errors in the negative direction.

Table 10-8The data in each ring plot series
Element Type Example
Name A single textual element labeling the data series. {"Widgets"}
Value A series of numeric values. {1293, 2502, 3297, 1100, 2487}
Label A series of textual elements labeling each value. Generally, this series will have as many entries as there were in the "Value" series. {"North", "South", "Central", "East", "West"}
Error (+) A list of numeric values with as many elements as there were in the 'Value' list. These values can be in the same units as the numeric values in the 'Value' list, can be proportions or can be proportions multiplied by one hundred. {0.10, 0.12, 0.09, 0.11, 0.09}
Error (-) A list of numeric values with as many elements as there were in the 'Value' list. These values can be in the same units as the numeric values in the 'Value' list, can be proportions or can be proportions multiplied by one hundred. {0.08, 0.11, 0.10, 0.09, 0.11}

Ring plots provide two icons distinguishing the two different styles.

Ring plot sub-type and style options.

The icon for a ring plot with the style of displaying series in contiguous rings.

The icon for a ring plot with the style of displaying the outermost series separated from the rest.