Round Down (Spatial Analyst)

Available with Spatial Analyst license.

Available with Image Analyst license.

Summary

Returns the next lower integer value, just represented as a floating point, for each cell in a raster.

Illustration

OutRas = RoundDown(InRas1)

Usage

• Input values can be positive or negative.

• The output raster from this tool is always floating-point type, regardless of the input value type.

• If the input number has any values to the right of the decimal point, the output will be assigned the next lower integer value, but will be represented as a floating point number with no decimal portion. For example:

      Input   Output
       5.3     5.0
       4.9     4.0
       3.0     3.0
       6.5     6.0
      -0.2    -1.0
      -2.8    -3.0

• There is a difference between the Int tool and the Round Down tool. For example, given the following two values, Int always truncates the number:

  • 1.5 becomes 1
  • -1.5 becomes -1

  For the same two values, Round Down returns the following:

  • 1.5 becomes 1.0
  • -1.5 becomes -2.0

  Another difference is that Round Down outputs floating-point values, while Int only outputs integer values.

• 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	The input values to be rounded down. 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 result of rounding down the input values.	Raster

Python

RoundDown(in_raster_or_constant)

Name	Explanation	Data Type
in_raster_or_constant	The input values to be rounded down. 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 result of rounding down the input values.	Raster

Code sample

RoundDown example 1 (Python window)

This example rounds the values in the input raster to the next lower integer value and outputs a floating-point raster.

import arcpy
from arcpy import env
from arcpy.sa import *
env.workspace = "C:/sapyexamples/data"
outRoundDown = RoundDown("gwhead")
outRoundDown.save("C:/sapyexamples/output/outrd")

RoundDown example 2 (stand-alone script)

This example rounds the values in the input raster to the next lower integer value and outputs a floating-point raster.

# Name: RoundDown_Ex_02.py
# Description: Returns the next lower whole number for each cell 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 = "gwhead"

# Execute RoundDown
outRoundDRaster = RoundDown(inRaster)

# Save the output 
outRoundDRaster.save("C:/sapyexamples/output/outrounddown")

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