<< (Bitwise Left Shift) (arcpy.sa)
Summary
Performs a Bitwise Left Shift operation on the binary values of two input rasters.
Illustration
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OutRas = Raster("InRas1") << 1 |
Discussion
When using an operator with a raster input the result will be a raster. However, if all inputs are numbers, then the result is a number.
When multiple operators are used in an expression, they are not necessarily executed in left-to-right order. The operator with the highest precedence value will be executed first. For more information on operator precedence, see operator precedence table. You can use parentheses to control the execution order.
The bitwise operators work on 32-bit integers.
If floating-point values are input, they are converted to integer values through truncation before the bitwise operation is performed. The output values are always integer.
Two inputs (rasters or numbers) are necessary for the bitwise operation to take place.
The order of input is relevant in the Bitwise Left Shift operation.
Binary values are stored in two's complement.
The leftmost bit position is reserved for the sign of the value (positive or negative). If the integer is positive, the bit position is zero; if it's negative, the bit position is one.
The Bitwise Left Shift operation does no wrapping of bits. The leftmost bit is dropped.
Another way to perform the Bitwise Left Shift operation is a <<= b, which is an alternative way to write a = a << b.
Syntax
| Operand | Explanation | Data Type |
in_raster_or_constant1 | The input raster on which to perform the shift. The input can be integer or floating point, but floating-point values will be converted to integer before the bitwise operation is performed. If the first input is a raster and the second is a scalar, an output raster is created with each input raster value being bitwise left shifted by the scalar value. | Raster Layer | Constant |
in_raster_or_constant2 |
The input raster defining the number of positions to shift the bits. The input can be integer or floating point, but floating-point values will be converted to integer before the bitwise operation is performed. If the first input is a scalar and the second is a raster, an output raster is created with each input raster value defining the bitwise left shift for the scalar value. | Raster Layer | Constant |
Return Value
| Name | Explanation | Data Type |
| out_raster |
The output raster object. The cell values are the result of a Bitwise Left Shift operation on the inputs. | Raster |
Code Sample
This sample performs a Bitwise Left Shift operation on two input rasters.
import arcpy
from arcpy import env
from arcpy.sa import *
env.workspace = "C:/sapyexamples/data"
outBitwiseLS = Raster("degs") << Raster("negs")
outBitwiseLS.save("C:/sapyexamples/output/outbitls.tif")
This sample performs a Bitwise Left Shift operation on two input rasters.
# Name: Op_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 = Raster("degs")
inRaster2 = Raster("negs")
# Check out the ArcGIS Spatial Analyst extension license
arcpy.CheckOutExtension("Spatial")
# Execute BitwiseLeftShift
outBitwiseLShift = inRaster1 << inRaster2
# Save the output
outBitwiseLShift.save("C:/sapyexamples/output/outlshift")