A general notion of a chart unites several different graphic representations of data series in ObjectLand. These representation are called types of charts. There are six types of charts all in all:
Area – for every group of data segments are measured proportionally to values of all data elements along the vertical line. Points corresponding to one series of different groups are linked by a curved line. The region under the curved line is displayed with fill style set for this data element.
Horizontal Bar – the value of each element is displayed as a horizontal bar the length of which is proportional to the element value. For every group of data its own set of lines is displayed, data series are highlighted by the color of the lines.
Bar – similarly to the type Horizontal bar, but instead of horizontal bars vertical columns are displayed.
Line – every data element is represented by a point vertical coordinate of which is proportional to the element value. In the case of several groups of data points corresponding to one data series are linked by a broken line (similarly to the type Area but without fill).
Pie – every group of data is displayed as a circle divided into sectors angular sizes of which are proportional to values of data elements.
Scatter – two data series are displayed as a set of points horizontal coordinate of which is taken from one data series, and the vertical one – from another series.
Some types of charts have several subtypes:
Simple –the value of the data element is measured from the coordinate axis.
Stacked – the value of the data element is measured from the previous element.
Percentage – as in Stacked subtype, but not absolute values of data elements are displayed, but percentage ratio of data element values to the sum of all elements of the group is displayed instead of their absolute values.
Below we will examine all types of charts on the example of the query “Allocation of Inhabitants by Streets” described above.
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