The data series of the Xceed Chart for WinForms component have built-in support for filtering. In general, filtering represents the ability to extract a data series subset based on user-specified criteria.

Performing a Filter Operation

The filtering functionality of the data series is exposed by the Filter method of the DataSeries class. Filter operations can be performed only on data series of type Double. If you attempt to execute the Filter method on a data series of another type, the component will raise an exception. The Filter command receives two arguments: the compare method that will be used and the compare value. The method will return an instance of a DataSeriesSubset object containing the indexes of the values in the data series matching the specified criteria. 

The following code retrieves the subset of bar values that are less than 50.

Dim subset As DataSeriesSubset =   barseries.Values.Filter(CompareMethod.Less,50)

DataSeriesSubset subset = barseries.Values.Filter(CompareMethod.Less, 50);

Compare Methods Supported by Filter Function

The compare method passed to the Filter function is of type CompareMethod, which has the following fields (for details, see CompareMethod Enumeration): 

More
Less
Equal
MoreOrEqual
LessOrEqual
NotEqual 

Internally the filter method iterates through the data series values and performs the compare method against the current value. If the current value satisfies the specified criteria, its index is added to the returned subset. The following table describes the operation performed by each compare method: 

Implementing Complex Filtering

In conjunction with the powerful set operations implemented by the DataSeriesSubset class, the user can implement complex filtering of the data. The following example generates an array of the data series values that are greater than 35 and less than 85.

Dim s1 As DataSeriesSubset,s2 As DataSeriesSubset
 
s1 = bar.Values.Filter(CompareMethod.More, 35)
s2 = bar.Values.Filter(CompareMethod.Less, 85)
 
s1.Intersect(s2)
 
Dim arrValues As ArrayList =  New ArrayList()
Dim index As Integer
 
For Each index In s1
    arrValues.Add(bar.Values(index))
Next

DataSeriesSubset s1, s2;

s1 = bar.Values.Filter(CompareMethod.More, 35);
s2 = bar.Values.Filter(CompareMethod.Less, 85);

s1.Intersect(s2);

ArrayList arrValues = new ArrayList();

foreach (int index in s1)
{
   arrValues.Add(bar.Values[index]);
}

Related Examples

Windows Forms: Data Manipulation\General\Filtering

See Also

Data Series Subsets | DataSeries | DataSeriesSubset