# 3.8.13: Mapper 🔷

![Fig. 3.8.13.1: The “Mapper”-component applies mappings to a given model](/files/-M9XuWbUxPvIttpUZSaT)

A **“Mapper”** is a component that takes a Karamba3D-model and modifies it according to some generic rules defined by mappings, based on parameters supplied by the user. It acts directly on the model, so the process of transferring Grasshopper-geometry to a Karamba3D-model is dispensed with. The resulting gain of speed can be important when running optimization tasks with e.g. Galapagos. Fig. 3.8.13.1 shows a definition where a mapper applies a mapping called **“Simple Stitch”** on a given model which originally consists of two elements: “A” and “B”. In this case there is one mapping that connects two beam-sets with elements whose position is controlled by the parameters given to the mapper. In other words: a mapping is a functor.

The input-plug **“Params”** receives two parameters. In the context of the **“Simple Stitch”**-mapping these parameters give the relative position on the two beam-sets “A” and “B” where a connection “C” shall be introduced. So a mapping encapsulates an operation and the mapper activates it. Currently Karamba3D offers mappings which mainly deal with connecting existing beam-sets by variants of an operation termed “stitching”. The notion comes from the analogy to joining together pieces of cloth. The stitching component is rooted in the research project *“*[*Algorithmic Generation of Complex Space Frames*](https://www.dieangewandte.at/jart/prj3/angewandte-2016/main.jart?rel=en\&reserve-mode=active\&content-id=1453407076279\&projekt_id=1461046078597)*”* which was conducted at the University of Applied Arts Vienna.


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