Semivariogram Sensitivity (Geostatisical Analyst)

Summary

Performs a sensitivity analysis with varying Nugget, Partial Sill, and Range values.

Learn more about how Semivariogram Sensitivity works

Usage

• The geostatistical model source is either a geostatistical layer or a geostatistical model (XML).

• This tool uses a random number generator in its operation. The Seed value used can be controlled in the Random number generator environment.

  • If a seed value of 0 is used (the default value), then each time the tool is run, a different set of random numbers will be used and a different output will be generated.
  • If the random number seed is set to a fixed number greater than 0, then the tool will produce the same output each time it is run, until the seed value is changed.
  Note:

  Only the MERSENNE_TWISTER random number generator type is supported; if ACM599 or STANDARD_C is chosen, MERSENNE_TWISTER will be used instead.

• In Python scripting, the GeostatisticalDatasets ArcPy class will be useful for populating the Input dataset(s) parameter.

• For data formats that support Null values, such as file and personal geodatabase feature classes, a Null value will be used to indicate that a prediction could not be made for that location or that the value should be ignored when used as input. For data formats that do not support Null values, such as shapefiles, the value of -1.7976931348623158e+308 is used (this is the negative of the C++ defined constant DBL_MAX) to indicate that a prediction could not be made for that location.

Syntax

GASemivariogramSensitivity_ga (in_ga_model_source, in_datasets, in_locations, {nugget_span_percents}, {nugget_calc_times}, {partialsill_span_percents}, {partialsill_calc_times}, {range_span_percents}, {range_calc_times}, {minrange_span_percents}, {minrange_calc_times}, out_table)

Parameter	Explanation	Data Type
in_ga_model_source	The geostatistical model source to be analyzed.	File; Geostatistical Layer
in_datasets	A GeostatisticalDatasets object. Alternatively, it can be a semicolon-delimited string of elements. Each element is comprised of the following components: The catalog path and name to a dataset or the name of a layer in the current table of contents, followed by a space. A sequence of field names, each field name separated by a space. In the case of a raster, the cell values will be used.	Geostatistical Value Table
in_locations	Point locations where the sensitivity analysis is performed.	Feature Layer
nugget_span_percents (Optional)	The percentage subtracted and added to the Nugget parameter to create a range for a subsequent random Nugget parameter selection.	Double
nugget_calc_times (Optional)	Number of random Nugget values drawn from the Nugget span.	Long
partialsill_span_percents (Optional)	Percentage subtracted from and added to the Partial Sill parameter to create a range for a random Partial Sill selection.	Double
partialsill_calc_times (Optional)	Number of random Partial Sill values drawn from the Partial Sill span.	Long
range_span_percents (Optional)	Percentage subtracted and added to the Major Range parameter to create a range for a random Major Range selection.	Double
range_calc_times (Optional)	Number of random Major Range values drawn from the Major Range span.	Long
minrange_span_percents (Optional)	Percentage subtracted and added to the Minor Range parameter to create a range for a random Minor Range selection.	Double
minrange_calc_times (Optional)	Number of random Minor Range values drawn from the Minor Range span. If Anisotropy has been set in <in_geostat_layer>, a value is required.	Long
out_table	Table storing the sensitivity results.	Table

Code Sample

SemivariogramSensitivity example 1 (Python window)

Performs a sensitivity analysis by varying the Nugget, Partial Sill, and Range values.

import arcpy
arcpy.env.workspace = "C:/gapyexamples/data"
arcpy.GASemivariogramSensitivity_ga(
    "C:/gapyexamples/data/kriging.lyr", "C:/gapyexamples/data/ca_ozone_pts.shp OZONE",
    "C:/gapyexamples/data/obs_pts.shp", "", "", "", "", "", "", "", "", 
    "C:/gapyexamples/output/outtabSS")

SemivariogramSensitivity example 2 (stand-alone script)

Performs a sensitivity analysis by varying the Nugget, Partial Sill, and Range values.

# Name: SemivariogramSensitivity_Example_02.py
# Description: The semivariogram parameters Nugget, Partial Sill and Range can
#   be varied to perform a sensitivity analysis.
# Requirements: Geostatistical Analyst Extension

# Import system modules
import arcpy

# Set environment settings
arcpy.env.workspace = "C:/gapyexamples/data"

# Set local variables
inLayer = "C:/gapyexamples/data/kriging.lyr"
inData = "C:/gapyexamples/data/ca_ozone_pts.shp OZONE"
inObs = "C:/gapyexamples/data/obs_pts.shp"
nugPercents = ""
nugCalc = ""
sillPercents = ""
sillCalc = ""
rangePercents = ""
rangeClac = ""
minrangePercent = ""
midrangeCalc = ""
outTable = "C:/gapyexamples/output/outtabSS"

# Check out the ArcGIS Geostatistical Analyst extension license
arcpy.CheckOutExtension("GeoStats")

# Execute SemivariogramSensitivity
arcpy.GASemivariogramSensitivity_ga(inLayer, inData, inObs, nugPercents, nugCalc,
                                    sillPercents, sillCalc, rangePercents, rangeClac,
                                    minrangePercent, midrangeCalc, outTable)

Environments

Current Workspace, Random number generator, Scratch Workspace

Licensing Information

ArcGIS for Desktop Basic: Requires Geostatistical Analyst

ArcGIS for Desktop Standard: Requires Geostatistical Analyst

ArcGIS for Desktop Advanced: Requires Geostatistical Analyst