Log2 (Spatial Analyst)

Available with Spatial Analyst license.

Available with Image Analyst license.

Summary

Calculates the base 2 logarithm of cells in a raster.

Illustration

OutRas = Log2(InRas1)

Usage

• The input can be of integer or float type.

  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.

• If the input is a multiband raster, the output will be a multiband raster. The tool will perform the operation on each band in the input.

• In ArcPy, if the input is a multidimensional raster, all slices from all variables will be processed, and the output will be a multidimensional raster.

• See Analysis environments and Spatial Analyst for additional details on the geoprocessing environments that apply to this tool.

Parameters

Dialog

Label	Explanation	Data Type
Input raster or constant value	Input values for which to find the base 2 logarithm. 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

Label	Explanation	Data Type
Output raster	The output raster. The cell values are the base 2 logarithm of the input values.	Raster

Python

Log2(in_raster_or_constant)

Name	Explanation	Data Type
in_raster_or_constant	Input values for which to find the base 2 logarithm. 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 2 logarithm of the input values.	Raster

Code sample

Log2 example (Python window)

This example calculates base 2 logarithm of the input raster values and generates the output as an IMG raster.

import arcpy
from arcpy import env
from arcpy.sa import *
env.workspace = "C:/sapyexamples/data"
outLog2 = Log2("elevation")
outLog2.save("C:/sapyexamples/output/outlog2.img")

Log2 example 2 (stand-alone script)

This example calculates base 2 logarithm of the input raster values.

# Name: Log2_Ex_02.py
# Description: Calculates the base 2 logarithm 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 = "degs"

# Execute Log2
outLog2 = Log2(inRaster)

# Save the output 
outLog2.save("C:/sapyexamples/output/outlog2")

Environments

Auto Commit, Cell Size, Cell Size Projection Method, Current Workspace, Extent, Geographic Transformations, Mask, Output CONFIG Keyword, Output Coordinate System, Scratch Workspace, Snap Raster, Tile Size

Licensing information

• Basic: Requires Spatial Analyst or Image Analyst
• Standard: Requires Spatial Analyst or Image Analyst
• Advanced: Requires Spatial Analyst or Image Analyst