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Data Aggregation

The chart control supports aggregating its data to reduce the number of data points displayed.

Aggregation Factor

In order to increase performance, the chart control will automatically determine the optimal number of data points to display based on the size of the control. This is determined using the AggregationFactor property, which defaults to 0.2.

For example, if the chart control is 100 pixels wide and uses an aggregation factor of 0.1, then the optimal number of data points would be 10. If the data source contained 1000 items, then the chart would create 10 groups, each with 100 items in it. Then some sort of aggregation function would be performed on each group to generate a single data point for display.

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A line series with markers visible with no aggregation, 10% aggregation, and 50% aggregation

Aggregation is enabled by default and can be disabled by setting IsAggregationEnabled to false.

Aggregation Kinds

There are various aggregation functions that can be performed on the items in a group. The supported aggregation kinds are specified using the PrimaryAggregationKind and SecondaryAggregationKind.

The PrimaryAggregationKind is typically used for the Y values, but for vertically-oriented series this will be used by the X values. Similarly, the SecondaryAggregationKind is used for X values, but will be used by Y values for vertically-oriented series.

The following table lists the supported aggregation kinds:

Aggregation Kind Description
Average Averages all the values in the group and uses that as the aggregated value.
First Uses the first value in the group as the aggregated value.
Last Uses the last value in the group as the aggregated value.
Maximum Uses the maximum value in the group as the aggregated value.
Minimum Uses the minimum value in the group as the aggregated value.
SignedMaximum Uses the value with the maximum absolute value in the group as the aggregated value. For example, 4 is greater than -5, but -5 has a greater absolute value.
SignedMinimum Uses the value with the minimum absolute value in the group as the aggregated value. For example, -4 is less than 3, but 3 has a lesser absolute value.