Table of Contents
TGIS_StatisticsAbstract class
DK11 for ActiveX | TatukGIS_XDK11.TGIS_StatisticsAbstract | Classes | Methods | Properties
General statistics class. Must be derived.
Syntax
// C# public class TGIS_StatisticsAbstract : ITGIS_StatisticsAbstract { }
' VisualBasic Public Class TGIS_StatisticsAbstract Implements ITGIS_StatisticsAbstract End Class
// Oxygene type TGIS_StatisticsAbstract = public class end;
Implements
Methods
| Name | Visibility | Description | |
|---|---|---|---|
| Add | public | Adds statistics result definition. | |
| AddAll | public | Adds statistics result definitions for all available datasets. | |
| AddAll_2 | public | Adds statistics result definitions for all available datasets. | |
| Add_2 | public | Adds statistics result definition. | |
| Add_3 | public | Adds statistics result definition. | |
| Add_4 | public | Adds statistics result definition. | |
| AttachDelphiObj | public | Only for internal use of TatukGIS. (Inherited from ITBaseObject) |
|
| Calculate | public | Calculate requested statistics from the entire layer. | |
| Calculate_2 | public | Calculate requested statistics from filtered elements of the layer. | |
| DelphiObj | public | Only for internal use of TatukGIS. (Inherited from ITBaseObject) |
|
| Get | public | Get statistics result by name. | |
| LoadFromFile | public | Parse statistics file and load all information into parent layer. | |
| LoadFromFile_2 | public | Parse statistics file and load all information into parent layer. | |
| Reset | public | Resets statistics object to initial state. | |
| ResetModified | public | Undo changes in requested statistics definitions. | |
| SaveToFile | public | Save layer statistics into auxiliary file. | |
| SaveToFile_2 | public | Save layer statistics into auxiliary file. | |
Properties
| Name | Visibility | Description | |
|---|---|---|---|
| Age | public | Age of the statistics. | |
| AvailableResults | public | List of available results names; read-only. | |
| DefinedResults | public | List of already defined results names; read-only. | |
| FastStatistics | public | Determines the state if 'Fast Statistics' was computed; read-only. | |
| Modified | public | True if requested statistics have changed. | |
| Obsolete | public | Check validity of statistics. | |
| UseBesselCorrection | public | If True, statistics class will use Bessel's correction. | |
Remarks
This class provide access to generating, saving and loading layer's statistics.
TGIS_StatisticalFunction enum contains a list of available statistical functions. These functions are also presented in the table below.
| Function name | Basic | Standard | All | Description |
|---|---|---|---|---|
| Average | + | + | + | The average value (arithmetic mean) of dataset. |
| Count | + | + | + | Number of valid elements in dataset (not empty, not null). |
| CountMissings | + | + | Number of empty or null elements in dataset. | |
| Max | + | + | + | The maximum value in dataset. |
| Majority | + | The value that occurs most often in dataset. | ||
| Median | + | + | The median (middle value) of dataset. | |
| Min | + | + | + | The minimum value in dataset. |
| Minority | + | The value that occurs least often in dataset. | ||
| Range | + | + | The difference between maximum and minimum values in dataset. | |
| StandardDeviation | + | + | The standard deviation of dataset. | |
| Sum | + | + | + | The sum of values in dataset. |
| Variance | + | + | The variance of dataset. | |
| Variety | + | The number of unique values in dataset. | ||
| Unique | + | Extracting unique values from dataset. |
TGIS_StatisticalFunctions is used to define requested statistics. Predefined groups can be used:
EmptyStatistics,BasicStatistics,StandardStatistics(this is default),AllStatistics.
Statistical results can be narrowed by setting Extent, Shape, Relation properties.
By default, the statistics engine calculates population standard deviation and variance (divider equals “N”). Sample variance and standard deviation (divider equals “N-1”) can be calculated by setting UseBesselCorrection to True.
See:
Example
Pseudocode:
// add all fields from vector layer or bands from pixel layer layer.Statistics.AddAll(TGIS_StatisticalFunctions.BasicStatistics); layer.Statistics.Calculate; // demand a result stats_result = layer.Statistics.Get(<valid_name>);
Valid names are listed in the stats.AvailableResults list.
// check calculated values average = stats_result.Average.Value; count = stats_result.Count.Value; min = stats_result.Min.Value; max = stats_result.Max.Value; sum = stats_result.Sum.Value;