AF SDK Reference

AFSearch.FrequencyDistributionAsync Method

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AFSearch.FrequencyDistributionAsync Method

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Last UpdatedNov 18, 2025
3 minute read

Generates a frequency distribution for the specified items asynchronously.

Namespace: OSIsoft.AF.Search
Assembly: OSIsoft.AFSDK (in OSIsoft.AFSDK.dll) Version: 3.1.1.1182

Syntax

public Task<AFGroupedResult<Object>> FrequencyDistributionAsync(
	string groupedField,
	CancellationToken cancellationToken
)

Public Function FrequencyDistributionAsync ( 
	groupedField As String,
	cancellationToken As CancellationToken
) As Task(Of AFGroupedResult(Of Object))

Dim instance As AFSearch
Dim groupedField As String
Dim cancellationToken As CancellationToken
Dim returnValue As Task(Of AFGroupedResult(Of Object))

returnValue = instance.FrequencyDistributionAsync(groupedField, 
	cancellationToken)

public:
Task<AFGroupedResult<Object^>^>^ FrequencyDistributionAsync(
	String^ groupedField, 
	CancellationToken cancellationToken
)

member FrequencyDistributionAsync : 
        groupedField : string * 
        cancellationToken : CancellationToken -> Task<AFGroupedResult<Object>>

Parameters

groupedField: Type: SystemString
The field whose value should be grouped.
cancellationToken: Type: System.ThreadingCancellationToken
A token to control cancellation of the aggregation request.

Return Value

Type: TaskAFGroupedResultObject
A result containing the requested frequency distribution or an error if the summaries could not be performed.

Remarks

Notes to Callers
This call might use a background task to complete some of its work. See the Threading Overview for some matters to consider when execution transitions to another thread.

Examples

// Get the Database
PISystems myPISystems = new PISystems();
PISystem myPISystem = myPISystems.DefaultPISystem;
if (myPISystem == null)
    throw new InvalidOperationException("Default PISystem was not found.");
AFDatabase myDB = myPISystem.Databases[dbName];
if (myDB == null)
    throw new InvalidOperationException("Database was not found.");

// Create a search to find all the event frames created from the 'Event'
// template in the last year.
using (AFEventFrameSearch eventSearch = new AFEventFrameSearch(myDB, "EventFrameSearch", @"Template:'Event' Start:>'t-1y'"))
{
    eventSearch.CacheTimeout = TimeSpan.FromMinutes(10);
    // Generate a frequency distribution by primary element
    AFGroupedResult<object> frequencyDistribution = await eventSearch.FrequencyDistributionAsync("Element", CancellationToken.None);
    foreach (var group in frequencyDistribution.GroupedResults)
    {
        Console.WriteLine("Element: {0}, Count: {1}",
            group.Key, group.Value[AFSummaryTypes.Count]);
    }
}

' Get the Database
Dim myPISystems As New PISystems()
Dim myPISystem As PISystem = myPISystems.DefaultPISystem
If myPISystem Is Nothing Then
    Throw New InvalidOperationException("Default PISystem was not found.")
End If
Dim myDB As AFDatabase = myPISystem.Databases(dbName)
If myDB Is Nothing Then
    Throw New InvalidOperationException("Database was not found.")
End If

' Create a search to find all the event frames created from the 'Event'
' template in the last year.
Using eventSearch As New AFEventFrameSearch(myDB, "EventFrameSearch", "Template:'Event' Start:>'t-1y'")
    eventSearch.CacheTimeout = TimeSpan.FromMinutes(10)


    ' Generate a frequency distribution by primary element
    Dim frequencyDistribution As AFGroupedResult(Of Object) = Await eventSearch.FrequencyDistributionAsync("Element", CancellationToken.None)
    For Each group As KeyValuePair(Of Object, IReadOnlyDictionary(Of AFSummaryTypes, AFValue)) In frequencyDistribution.GroupedResults
        Console.WriteLine("Element: {0}, Count: {1}", group.Key, group.Value(AFSummaryTypes.Count))
    Next

    Return True
End Using

No code example is currently available or this language may not be supported.

Version Information

AFSDK

Supported in: 3.1.1, 3.1.0, 3.0.2, 3.0.1, 3.0.0, 2.10.11, 2.10.5, 2.10.0, 2.10, 2.9.5, 2.9

AF SDK Reference