Friday, November 18, 2016

HeatSpace for NetLogo

I have put up a beta version of heatspace. This program generates visualizations for Netlogo's BehaviorSpace. Find the program and manual here:
NetLogo is an agent-based modeling platform whose ease of use and functionality are hard to beat. The goal of this manual is to succinctly show how to generate visualizations that present significant portions of a model's parameter space. Those who are not accustomed to agent-based modeling may expect visualizations to come in the form of line plots. Line plots are an easy way to convey a limited amount of information to a user, but it is difficult to convey more than a few lines without confusing the observer. Instead of representing the value of an output spatially, heatmaps represent value using color.

When we visualize the parameter space, it is not enough to represent this space only using a single run for each combination of parameters. Each combination must be mapped using a substantial number of runs. Usually 20 runs may produce a large enough sample to faithfully represent the parameter space. More is better. If generating data from model of interest is not a high cost endeavor, use more runs.

HeatSpace averages the values generated at each time period during a run. These values can then mapped onto two axes whose values are fixed throughout a run . A single map can be generated for each time period of a run, creating series of frames analogous to a movie. Alternately, the x-axis of a heatmap can represent time so that the change in the value of an output in light of a change in either the x or y parameter value at period t can be represented.

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