Map Algebra

ArcGIS Spatial Analyst includes advanced map algebra functions for combining multiple maps, performing suitability analysis, assigning weights, and identifying relationships.

This graphic illustrates how mathematical operators and functions can be used to combine data on a cell-by-cell basis to derive new information.

Map algebra provides an easy-to-use and powerful way to define geographic analysis as algebraic expressions. This allows users to take their real world data and apply algebraic functions to derive new results.

For example, a single expression can be constructed to find the combined value of two datasets [(Raster1) + (Raster2)]. These algebraic expressions can be simple arithmetic expression or can consist of complex spatial and algebraic functions.

You can build complex expressions and process them as a single command. For example, you can use a single expression to find all the cells within a specific elevation range, apply a unit conversion such as feet to meters, and calculate the slope at each of those cells. Such an expression might look like the following: