Mapper

Mapper is a term with several related meanings, all centered on the idea of transformation or representation. It can describe a person who creates maps, a software component that translates data from one representation to another, or a method for extracting structure from complex information.

In cartography and geography, a mapper is a person who designs and produces maps for navigation, planning, or education. Modern mappers rely on geographic information systems, aerial and satellite imagery, and field surveying.

In software engineering, a mapper denotes a component or pattern that translates between two data representations. The data mapper pattern and object-relational mappers (ORMs) separate in-memory domain objects from persistence concerns. This decouples business logic from storage, enabling developers to work with domain models while a mapping layer handles database schema. Examples include Hibernate and Entity Framework. The data mapper pattern was articulated by Martin Fowler.

In topological data analysis, Mapper is a specific algorithm that builds a graph-like representation of high-dimensional data by covering the data with overlapping intervals, clustering within each cover, and connecting clusters that share data points. It provides a qualitative view of the data's shape.

In hardware and video games, a memory mapper is a device in some game cartridges that remaps CPU and PPU address spaces to extend practical memory. In other contexts, "mapper" may simply refer to software modules that map inputs to outputs in a pipeline or interface layer.