Pie Plots

Pie plots present the numeric values from a single series of categorical data as slices of a circular area, the angular arc of each slice determined by the proportional magnitude of each value compared to the overall sum of all the values. For example, if the series had values { 1.12, 4.48, 3.36, 1.68, 0.56}, the contribution of each slice 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 wedges would be {36, 144, 108, 54, 18} degrees, since 36=0.10*360.

Pie plots do not have any sub-types.

Pie plot styles provide two choices for the rendering of the pie chart, either with all slices linked into one overall circle, or with gaps between the slices. The size of the gap is a property of the pie plot which can be changed.

Figure 10-9 An example of a pie plot

This screenshot shows a table of data and a pie plot. The data consist of a single data series organized in a row and starting with the word "Widgets". The series has values in five categories. The legend includes the names of the different data categories.

Each pie plot contains a single series which can include three 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 legend added to a pie plot identifies the different categories using the entries in the 'Label' element.

Table 10-6 The data in each pie plot series

Element	Type	Example
Name	A single textual entry labeling the data series.	{"Widgets"}
Value	A list of numeric values.	{1293, 2502, 3297, 1100, 2487}
Label	A list of textual entries labeling the category of each value. Generally, this series will have as many entries as there were in the 'Value' list. These will be used in the legend which may be displayed with the pie plot.	{"North", "South", "Central", "East", "West"}

Pie plots do not have any sub-types but provide two icons to distinguish the style of the plot allowing a choice between pie plots which comprise a single circular area or plots with distinct pie slices separated by small gaps.

Line plot sub-type and style options.

: The icon for a pie plot of the style with joint slices.
: The icon for a pie plot of the style with separated slices.