Understanding the OPUS User Guide

Sometimes it's hard while learning to know what's really significant or important. Like reading big chunks of a 300 page manual in depth, I think I'd find it hard to make a compelling case for things like how the MNL (multinomial logit) model is an efficient discrete choice model for doing things like modelling economic utility (assuming I'm not mincing terms together).


But let's not let that detract from some useful or interesting pieces (at least for me) which really have helped to establish some meaningful context.

For a start, let's read into how the manual is structured. The 6 graph nodes represent chapters in order in the OPUS manual. I've added some comments from my understanding so far of the actual implementation's useful features:

 

Let's consider some other diagrams in the OPUS User Guide. 

OPUS User Guide v4.3, Page 32, Chapter 7.1, Figure 7.2: Opus databases, datasets and arrays

A good clarification of concepts, including in the surrounding text that these .li4 files are just numpy arrays. As implied earlier, we'd get data into this format by using the import tools on the Data->Tools tab.

OPUS User Guide v4.3, Page 96, Chapter 17.2.1, Figure 17.3: Overview of UrbanSim Model System

Note: A similar if not equivalent diagram (with a different visual style) appears as Figure 2.1: UrbanSim Model Components and Data Flow on page 15.

This overview is explained to be the general template many urban planners use to calibrate their instance of UrbanSim. We can easily see the important and required inputs and other likely dependencies for which data will need to be identified (or synthesised / worked around) in order to get a new city into OPUS, and which models such data is relevant to.

OPUS User Guide v4.3, Page 54, Chapter 10.2.1, Figure 10.2: Using the "Result Browser" for interactive result exploration

And then there's the that's (hopefully) just plain cool diagrams!