Bitwise Left Shift (Spatial Analyst)

Available with Spatial Analyst license.

Available with Image Analyst license.

Summary

Performs a Bitwise Left Shift operation on the binary values of two input rasters.

Learn more about how Bitwise Math tools work

Illustration

OutRas = BitwiseLeftShift(InRas1, 1)

Usage

• Two inputs are necessary for this bitwise operation to take place.

• The order of inputs is relevant for this tool.

• If an input is floating point, the values are converted to integer values through truncation before the bitwise operation is performed.

• In bitwise operations the following are true:

  • Binary values are stored in two's complement.
  • The tools work on 32-bit integers.
  • The leftmost bit position is reserved for the sign (positive or negative) of the value. If the integer is positive, the bit position is 0; if it's negative, the bit position is 1.

• The Bitwise Left Shift operation does no wrapping of bits. The leftmost bit is dropped.

• If both inputs are single band rasters or one of the inputs is a constant, the output will be a single band raster.

• If both inputs are multiband rasters, the tool will perform the operation on each band from one input, and the output will be a multiband raster. The number of bands in each multiband input must be the same.

• If one of the inputs is a multiband raster and the other input is a constant, the tool will perform the operation using the constant value for each band in the multiband input, and the output will be a multiband raster.

• In ArcPy, if both inputs are multidimensional rasters with the same number of variables, the tool will perform the operation for all slices with the same dimension value, and the output will be a multidimensional raster. The variables in the inputs must have the same dimensions or common dimension but no uncommon dimensions.

  If both inputs have one variable but different names, set the matchMultidimensionalVariable geoprocessing environment to False to perform the operation.

  In ArcPy, if one of the inputs is a multidimensional raster and the other input is a constant, the tool will perform the operation for all slices for all variables using the constant value, and the output will be a multidimensional raster.

• In Map Algebra, the equivalent operator symbol for this tool is "<<" (link).

• 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 1	The input on which to perform the shift. A number can be used as an input for this parameter, provided a raster is specified for the other parameter. To specify a number for both inputs, the cell size and extent must first be set in the environment.	Raster Layer; Constant
Input raster or constant value 2	The input defining the number of positions to shift the bits. A number can be used as an input for this parameter, provided a raster is specified for the other parameter. To specify a number for both inputs, 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 result of a Bitwise Left Shift operation on the inputs.	Raster

Python

BitwiseLeftShift(in_raster_or_constant1, in_raster_or_constant2)

Name	Explanation	Data Type
in_raster_or_constant1	The input on which to perform the shift. A number can be used as an input for this parameter, provided a raster is specified for the other parameter. To specify a number for both inputs, the cell size and extent must first be set in the environment.	Raster Layer; Constant
in_raster_or_constant2	The input defining the number of positions to shift the bits. A number can be used as an input for this parameter, provided a raster is specified for the other parameter. To specify a number for both inputs, 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 result of a Bitwise Left Shift operation on the inputs.	Raster

Code sample

BitwiseLeftShift example 1 (Python window)

This example left-shifts the values of the first input by the number of bits defined by the second input, and outputs the result as a TIFF raster.

import arcpy
from arcpy import env
from arcpy.sa import *
env.workspace = "C:/sapyexamples/data"
outBitwiseLS = BitwiseLeftShift("degs", "negs")
outBitwiseLS.save("C:/sapyexamples/output/outbitls.tif")

BitwiseLeftShift example 2 (stand-alone script)

This example left-shifts the values of the first input by the number of bits defined by the second input.

# Name: BitwiseLeftShift_Ex_02.py
# Description: Performs a Bitwise Left Shift operation on the binary
#              values of two input rasters
# 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
inRaster1 = "degs"
inRaster2 = "negs"

# Execute BitwiseLeftShift
outBitwiseLShift = BitwiseLeftShift(inRaster1, inRaster2)

# Save the output 
outBitwiseLShift.save("C:/sapyexamples/output/outlshift")

Environments

Auto Commit, Cell Size, Cell Size Projection Method, Compression, 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