topic Re: C# IReadOnlyList<TableStatisticsResult> value(s)? in ArcGIS Pro SDK Questions

C# IReadOnlyList value(s)?

MikeRatcliffe — Tue, 17 Jul 2018 14:25:57 GMT

You provide a nice example of how to set up calculatestatistics here:

ProConcepts Geodatabase · Esri/arcgis-pro-sdk Wiki · GitHub

However, most folks (me) are interested in the actual values produced.

Can someone lead me in a direction to get an actual value from IReadOnlyList<TableStatisticsResult>?

I calculated a SUM of a field, but want to provide the value to a new variable for further calculation...

Thank You.

Re: C# IReadOnlyList value(s)?

BrianBulla — Sun, 12 Dec 2021 08:41:01 GMT

Yes, I have exactly the same question. I think I've been able to calculate the MAX value of a certain field, but I have no idea of how to actually get the value out of the TableStatisticsResult.

Any help is appreciated.

FeatureClass vlsFC = vlsLayer.GetFeatureClass();
FeatureClassDefinition fcd = vlsFC.GetDefinition();

Field fldVLS_NO_1 = fcd.GetFields().First(x => x.Name.Equals("VLS_NO_1"));
StatisticsDescription vlsMaxDesc = new StatisticsDescription(fldVLS_NO_1, new List<StatisticsFunction>() { StatisticsFunction.Max });
TableStatisticsDescription tsd = new TableStatisticsDescription(new List<StatisticsDescription>() { vlsMaxDesc });
IReadOnlyList<TableStatisticsResult> vlsStatsResult = vlsFC.CalculateStatistics(tsd);                                        

//This does not work
ArcGIS.Desktop.Framework.Dialogs.MessageBox.Show("Max VLS is " + vlsStatsResult.Max);‍‍‍‍‍‍‍‍‍‍

Re: C# IReadOnlyList value(s)?

UmaHarano — Mon, 23 Jul 2018 17:35:51 GMT

Hi Brian,

Try this:

var value = vlsStatsResult.First().StatisticsResults.First().Max;‍

Thanks

Uma

Re: C# IReadOnlyList value(s)?

BrianBulla — Mon, 23 Jul 2018 18:02:32 GMT

Great! Thanks Uma.

Re: C# IReadOnlyList value(s)?

RichRuh — Mon, 23 Jul 2018 18:33:11 GMT

To answer Mike's original question, I've expanded the snippet he posted to extract the calculation results. Here is the code:

// Calculate Statistics
IReadOnlyList<TableStatisticsResult> tableStatisticsResults = countryFeatureClass.CalculateStatistics(tableStatisticsDescription);

foreach(TableStatisticsResult tableStatisticsResult in tableStatisticsResults)
{
// Get the Region name
// If multiple fields had been passed into TableStatisticsDescription.GroupBy, there

// would be multiple values in TableStatisticsResult.GroupBy
string regionName = tableStatisticsResult.GroupBy.First().Value.ToString();

// Get the statistics results for the Population_1990 field
StatisticsResult pop1990Statistics = tableStatisticsResult.StatisticsResults[0];
double population1990Sum = pop1990Statistics.Sum;
double population1990Average = pop1990Statistics.Average;

// Get the statistics results for the Population_2000 field
StatisticsResult pop2000Statistics = tableStatisticsResult.StatisticsResults[1];
double population2000Sum = pop2000Statistics.Sum;
double population2000Average = pop2000Statistics.Average;

// Do something with the results here...

}

I hope this helps.

Re: C# IReadOnlyList value(s)?

MikeRatcliffe — Mon, 23 Jul 2018 18:41:58 GMT

Thanks, Uma.

".StatisticsResults.First().Max;" was all I needed to get moving again on my code.

Thanks, Rich for the expanded clarification.

Re: C# IReadOnlyList value(s)?

MikeRatcliffe — Thu, 16 Aug 2018 17:35:29 GMT

Coda to the original question:

How can I perform Table operations like .CalculateStatistics upon a FeatureLayer.GetSelection()?

i.e., converting a featurelayer selection (from user) into a temporary table so I can .CalculateStatistics.

Re: C# IReadOnlyList value(s)?

RichRuh — Tue, 21 Aug 2018 18:41:34 GMT

Hi Mike,

There is no direct way to do this. The best solution at this point is to create a temporary table from your selection using geoprocessing tools and use that to run Table.CalculateStatistics().

(I already answered in another thread, but wanted to duplicate the answer here in case others see it)

--Rich