# Sunburst

Not to be confused with circle graph. Pie charts are very widely used in the business world and the mass media. The earliest known pie chart is generally credited to William Playfair’s Statistical Breviary of 1801, in which two such graphs sunburst used. The French engineer Charles Joseph Minard was one of the first to use pie charts in 1858, in particular in maps.

Playfair thought that pie charts were in need of a third dimension to add additional information. It has been said that Florence Nightingale invented it, though in fact she just popularised it and she was later assumed to have created it due to the obscurity of Playfair’s creation. A 3d pie chart, or perspective pie chart, is used to give the chart a 3D look. Doughnut charts are similar to pie charts in that their aim is to illustrate proportions. A chart with one or more sectors separated from the rest of the disk is known as an exploded pie chart. This effect is used to either highlight a sector, or to highlight smaller segments of the chart with small proportions.

Diagram of the causes of mortality in the army in the East” by Florence Nightingale. The polar area diagram is similar to a usual pie chart, except sectors have equal angles and differ rather in how far each sector extends from the center of the circle. 1829 paper showing seasonal and daily variation in wind direction over the year and births and deaths by hour of the day. Léon Lalanne later used a polar diagram to show the frequency of wind directions around compass points in 1843.

A ring chart, also known as a sunburst chart or a multilevel pie chart, is used to visualize hierarchical data, depicted by concentric circles. The circle in the center represents the root node, with the hierarchy moving outward from the center. A variant of the polar area chart is the spie chart designed by Dror Feitelson. This superimposes a normal pie chart with a modified polar area chart to permit the comparison of two sets of related data. The base pie chart represents the first data set in the usual way, with different slice sizes. Square charts are a rare form of pie charts that use squares instead of circles to represent percentages. The following example chart is based on preliminary results of the election for the European Parliament in 2004.

The table lists the number of seats allocated to each party group, along with the derived percentage of the total that they each make up. Because of rounding, these totals do not add up to 100 and 360. The size of each central angle is proportional to the size of the corresponding quantity, here the number of seats. Q of the total is 360Q degrees.