Available with Spatial Analyst license.
Summary
Calculates the natural logarithm (base e) of cells in a raster.
Illustration
Usage
You can review some results for floating-point input values in the examples of output values from the Logarithmic tools.
Input values that are 0 or negative will be NoData in the output raster.
The output raster from this tool is always floating-point type, regardless of the input value type.
The natural logarithm (Ln) is the most commonly used logarithmic function.
See Analysis environments and Spatial Analyst for additional details on the geoprocessing environments that apply to this tool.
Syntax
Ln (in_raster_or_constant)
| Parameter | Explanation | Data Type |
in_raster_or_constant | Input values for which to find the natural logarithm (Ln). In order to use a number as an input for this parameter, the cell size and extent must first be set in the environment. | Raster Layer | Constant |
Return Value
| Name | Explanation | Data Type |
| out_raster | The output raster. The cell values are the base e (natural) logarithm of the input values. | Raster |
Code Sample
Ln example 1 (Python window)
This example calculates the natural logarithm (base e) of the input raster values.
import arcpy
from arcpy import env
from arcpy.sa import *
env.workspace = "C:/sapyexamples/data"
outLn = Ln("elevation")
outLn.save("C:/sapyexamples/output/outln2")
Ln example 2 (stand-alone script)
This example calculates the natural logarithm (base e) of the input raster values.
# Name: Ln_Ex_02.py
# Description: Calculates natural logarithm (base e) of cells in a raster
# Requirements: Spatial Analyst Extension
# Import system modules
import arcpy
from arcpy import env
from arcpy.sa import *
# Set environment settings
env.workspace = "C:/sapyexamples/data"
# Set local variables
inRaster = "elevation"
# Check out the ArcGIS Spatial Analyst extension license
arcpy.CheckOutExtension("Spatial")
# Execute Ln
outLn = Ln(inRaster)
# Save the output
outLn.save("C:/sapyexamples/output/outln")
Environments
Licensing Information
- ArcGIS for Desktop Basic: Requires Spatial Analyst
- ArcGIS for Desktop Standard: Requires Spatial Analyst
- ArcGIS for Desktop Advanced: Requires Spatial Analyst