private async void OnExecuteStatisticsQueryClicked(object sender, EventArgs e)
{
// Create definitions for each statistic to calculate
StatisticDefinition statDefinitionAvgPop = new StatisticDefinition("POP", StatisticType.Average, "");
StatisticDefinition statDefinitionMinPop = new StatisticDefinition("POP", StatisticType.Minimum, "");
StatisticDefinition statDefinitionMaxPop = new StatisticDefinition("POP", StatisticType.Maximum, "");
StatisticDefinition statDefinitionSumPop = new StatisticDefinition("POP", StatisticType.Sum, "");
StatisticDefinition statDefinitionStdDevPop = new StatisticDefinition("POP", StatisticType.StandardDeviation, "");
StatisticDefinition statDefinitionVarPop = new StatisticDefinition("POP", StatisticType.Variance, "");
// Create a definition for count that includes an alias for the output
StatisticDefinition statDefinitionCount = new StatisticDefinition("POP", StatisticType.Count, "CityCount");
// Add the statistics definitions to a list
List <StatisticDefinition> statDefinitions = new List <StatisticDefinition>
{
statDefinitionAvgPop,
statDefinitionCount,
statDefinitionMinPop,
statDefinitionMaxPop,
statDefinitionSumPop,
statDefinitionStdDevPop,
statDefinitionVarPop
};
// Create the statistics query parameters, pass in the list of definitions
StatisticsQueryParameters statQueryParams = new StatisticsQueryParameters(statDefinitions);
// If only using features in the current extent, set up the spatial filter for the statistics query parameters
if (_onlyInExtentSwitch.Checked)
{
// Get the current extent (envelope) from the map view
Envelope currentExtent = _myMapView.GetCurrentViewpoint(ViewpointType.BoundingGeometry).TargetGeometry as Envelope;
// Set the statistics query parameters geometry with the envelope
statQueryParams.Geometry = currentExtent;
// Set the spatial relationship to Intersects (which is the default)
statQueryParams.SpatialRelationship = SpatialRelationship.Intersects;
}
// If only evaluating the largest cities (over 5 million in population), set up an attribute filter
if (_onlyBigCitiesSwitch.Checked)
{
// Set a where clause to get the largest cities (could also use "POP_CLASS = '5,000,000 and greater'")
statQueryParams.WhereClause = "POP_RANK = 1";
}
// Execute the statistical query with these parameters and await the results
StatisticsQueryResult statQueryResult = await _worldCitiesTable.QueryStatisticsAsync(statQueryParams);
// Display results in a list in a dialog
var statsList = statQueryResult.FirstOrDefault().Statistics.ToList();
ShowStatsList(statsList);
}
private async void QueryStatistics(bool onlyInExtent, bool onlyLargePop)
{
// Create definitions for each statistic to calculate.
StatisticDefinition statDefinitionAvgPop = new StatisticDefinition("POP", StatisticType.Average, "");
StatisticDefinition statDefinitionMinPop = new StatisticDefinition("POP", StatisticType.Minimum, "");
StatisticDefinition statDefinitionMaxPop = new StatisticDefinition("POP", StatisticType.Maximum, "");
StatisticDefinition statDefinitionSumPop = new StatisticDefinition("POP", StatisticType.Sum, "");
StatisticDefinition statDefinitionStdDevPop = new StatisticDefinition("POP", StatisticType.StandardDeviation, "");
StatisticDefinition statDefinitionVarPop = new StatisticDefinition("POP", StatisticType.Variance, "");
// Create a definition for count that includes an alias for the output.
StatisticDefinition statDefinitionCount = new StatisticDefinition("POP", StatisticType.Count, "CityCount");
// Add the statistics definitions to a list.
List <StatisticDefinition> statDefinitions = new List <StatisticDefinition>
{
statDefinitionAvgPop,
statDefinitionCount,
statDefinitionMinPop,
statDefinitionMaxPop,
statDefinitionSumPop,
statDefinitionStdDevPop,
statDefinitionVarPop
};
// Create the statistics query parameters, pass in the list of definitions.
StatisticsQueryParameters statQueryParams = new StatisticsQueryParameters(statDefinitions);
// If only using features in the current extent, set up the spatial filter for the statistics query parameters.
if (onlyInExtent)
{
// Get the current extent (envelope) from the map view.
Envelope currentExtent = _myMapView.GetCurrentViewpoint(ViewpointType.BoundingGeometry).TargetGeometry as Envelope;
// Set the statistics query parameters geometry with the current extent.
statQueryParams.Geometry = currentExtent;
// Set the spatial relationship to Intersects (which is the default).
statQueryParams.SpatialRelationship = SpatialRelationship.Intersects;
}
// If only evaluating the largest cities (over 5 million in population), set up an attribute filter.
if (onlyLargePop)
{
// Set a where clause to get the largest cities (could also use "POP_CLASS = '5,000,000 and greater'").
statQueryParams.WhereClause = "POP_RANK = 1";
}
try
{
// Execute the statistical query with these parameters and await the results.
StatisticsQueryResult statQueryResult = await _worldCitiesTable.QueryStatisticsAsync(statQueryParams);
// Get the first (only) StatisticRecord in the results.
StatisticRecord record = statQueryResult.FirstOrDefault();
// Make sure a record was returned.
if (record == null || record.Statistics.Count == 0)
{
ShowMessage("No result", "No results were returned.");
return;
}
// Display results.
ShowStatsList(record.Statistics);
}
catch (ArcGISWebException exception)
{
ShowMessage("There was a problem running the query.", exception.ToString());
}
}