Tool parameters in Map Algebra

Available with Spatial Analyst license.

Tool parameters define how a tool processes input data. Tool parameters are composed of keywords, user-defined parameters, and classes.

Tool parameter rules

• A keyword parameter such as output_measurement has specific preset keywords (DEGREE, PERCENT_RISE), which are enclosed in quotation marks. Keywords are not case sensitive, but it is recommended that you capitalize them for readability.

  # Usage: Slope(in_raster, {output_measurement}, {z_factor})
  
  # DEGREE will be used as the default output measurement in the 
  #  following statement
  outRas = Slope("elevation", "DEGREE")

User-defined parameters are inputs that typically quantify a parameter.

• User-defined parameters are usually numbers and are not in quotation marks.

  # In the following statement 4 is the zfactor parameter
  outRas = Slope("inraster", "DEGREE", 4)

Some input parameters are classes. Classes are used when geoprocessing tool parameters would otherwise be a more complicated string equivalent.

• The specific arguments for the class are enclosed in parentheses. String input is in quotation marks, and numbers are not; parameters are comma delimited.

  outRas = FocalStatistics("inraster", NbrAnnulus(1, 3, "MAP"))

  For additional information, see Spatial Analyst classes.

• To specify a default value for an optional parameter, you must use empty quotation marks.

  # In the following statement the slope calculations will 
  #  default to DEGREE; 4 is the z value
  factoroutRas = Slope("inraster", "", 4)

Note:

For readability, it is recommended that you set the class object to a meaningfully named variable and use the variable in the Map Algebra tool.

myRemapVal = RemapValue([[-3,9],[0,1],[3,-4],[4,5],[5,6],[6,4],[7,-7]])
outReclassRV = Reclassify(inRaster, "VALUE", myRemapVal, "")