# << (Bitwise Left Shift) operator

## Summary

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

## Discussion

When using an operator with a raster input, the result will be a raster. However, if all inputs are numbers, the result is a number.

When there are multiple operators in an expression, the operators are not necessarily run in left-to-right order. The operator with the highest precedence value will be run first. For more information, see the operator precedence table in Work with operators in map algebra. Use parentheses to control the run 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.

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 operator 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 operator will perform the operation against the constant value for each band in the multiband input, and the output will be a multiband raster.

If both inputs are multidimensional rasters with the same number of variables, the operator 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 a common dimension but no uncommon dimensions.

If both inputs have one variable but different names, set the Match Multidimensional Variable environment to False to perform the operation.

If one of the inputs is a multidimensional raster and the other input is a constant, the operator will perform the operation for all slices for all variables against the constant value, and the output will be a multidimensional raster.

## Parameters

 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

## Code sample

<< (Bitwise Left Shift) example 1 (Python window)

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")``````
<< (Bitwise Left Shift) example 2 (stand-alone script)

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")

# Execute BitwiseLeftShift
outBitwiseLShift = inRaster1 << inRaster2

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