Trend (Spatial Analyst)

Summary

Interpolates a raster surface from points using a trend technique.

Learn more about how Trend works

Usage

Syntax

Trend (in_point_features, z_field, {cell_size}, {order}, {regression_type}, {out_rms_file})
ParameterExplanationData Type
in_point_features

The input point features containing the z-values to be interpolated into a surface raster.

Feature Layer
z_field

The field that holds a height or magnitude value for each point.

This can be a numeric field or the Shape field if the input point features contain z-values.

If the regression type is Logistic, the values in the field can only be 0 or 1.

Field
cell_size
(Optional)

The cell size at which the output raster will be created.

This will be the value in the environment if it is explicitly set; otherwise, it is the shorter of the width or the height of the extent of the input point features, in the input spatial reference, divided by 250.

Analysis Cell Size
order
(Optional)

The order of the polynomial.

This must be an integer between 1 and 12. A value of 1 will fit a flat plane to the points, and a higher value will fit a more complex surface. The default is 1.

Long
regression_type
(Optional)

The type of regression to be performed.

  • LINEAR Polynomial regression is performed to fit a least-squares surface to the set of input points. This is applicable for continuous types of data.
  • LOGISTIC Logistic trend surface analysis is performed. It generates a continuous probability surface for binary, or dichotomous, types of data.
String
out_rms_file
(Optional)

File name for the output text file that contains information about the RMS error and the Chi-Square of the interpolation.

The extension must be ".txt".

File

Return Value

NameExplanationData Type
out_raster

The output interpolated surface raster.

Raster

Code Sample

Trend example 1 (Python window)

This example inputs a point shapefile and interpolates the output surface as a TIFF raster.

import arcpy
from arcpy import env  
from arcpy.sa import *
env.workspace = "C:/sapyexamples/data"
outTrend = Trend("ozone_pts.shp", "ozone", 2000, 2, "LINEAR")
outTrend.save("C:/sapyexamples/output/trendout.tif")
Trend example 2 (stand-alone script)

This example inputs a point shapefile and interpolates the output surface as a GRID raster.

# Name: Trend_Ex_02.py
# Description: Interpolate a series of point features 
#    onto a rectangular raster using a trend technique.
# Requirements: Spatial Analyst Extension
# Author: ESRI

# Import system modules
import arcpy
from arcpy import env
from arcpy.sa import *

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

# Set local variables
inPointFeatures = "ca_ozone_pts.shp"
zField = "ozone"
cellSize = 2000.0
PolynomialOrder = 2
regressionType = "LINEAR"


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

# Execute Trend
outTrend = Trend(inPointFeatures, zField, cellSize, 
                 PolynomialOrder, regressionType)

# Save the output 
outTrend.save("C:/sapyexamples/output/trendout02")

Environments

Related Topics

Licensing Information

ArcView: Requires Spatial Analyst or 3D Analyst
ArcEditor: Requires Spatial Analyst or 3D Analyst
ArcInfo: Requires Spatial Analyst or 3D Analyst

6/29/2011