I've repeatedly come across the need to read or write Raster files in Java. These are data files which represent a rectangular grid of data using ASCII representations of numbers. An example, from GeoTools:
ncols 157
nrows 171
xllcorner -156.08749650000
yllcorner 18.870890200000
cellsize 0.00833300
nodata_value -9999
0 0 1 1 1 2 3 3 5 6 8 9 12 14 18 21 25 30 35 41 47 53
59 66 73 79 86 92 97 102 106 109 112 113 113 113 111 109 106
All values can be doubles or ints.
Crowdsourcing refers to using the general population to carry out tasks, often for free. Often, the idea is that by combining many inputs of unknown or variable quality, high quality outputs can be created - either through selection or some form of organisation.
I'm going to spend a couple of posts talking about some techniques I've been using while building and calibrating models, as they seem to be less well known than they might be. The first in this series is Sensitivity Analysis.
UA and SA are techniques to analyse the robustness of model outputs; that is, given a model, and certain assumptions about its input parameters (and their distributions), we would like to know how much we can trust the output. In general terms, Uncertainty Analysis gives us the amount of uncertainty (or variance) in the model output, while Sensitivity Analysis tells us how much of that variance is due to each of the input factors.
For the second time in two days, I came across the terms emic and etic, so it's time to have a bit more of a look into what they mean. This was prompted by a paper on JASSS1, which I found following up on the links between Prospect Theory and ABM. (Not while looking for ways to model crack dealers.)
So, it's a good time to be in the Agent Based Modelling (ABM) business. More and more attention is being given to the idea that while we have a certain level of understanding of the physical, chemical and biological processes around climate change, in order to change what's happening, we need to look at the social systems which are contributing.
Wednesday morning was the main reason I was here - the symposium on "Agent-Based Modelling of Land-use Effects", organised by Gary Polhill.
The second day at US-IALE was mostly taken up with the Coupled Human and Natural Systems (CHANS) discussion.
This week I'm attending the US-IALE conference in Snowbird, Utah, with the tagline "Coupling Humans and Complex Ecological Landscapes".
Started off in the Social Networks and Multi-Agent Systems room again, a talk by Davide Donetto, about "The emergence of shared social representations in complex networks". He talked about the difference between "reified" roles, which are selected by rules according to competences, and "consensual" roles, which are freely chosen by the agents. His model involved a social network of agents, constructed with a small world distribution, so that when a new node is added, the probability of it linking to an existing node is proportional to the share of the links that node has:
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I'm attending AISB09 in Edinburgh, talking about "Adaptive and Emergent Behaviour and Complex Systems"
I started in the Social Networks and Multi Agent Systems symposium, with "Leon van der Torre and Serena Villata. Four Ways to Change Coalitions: Agents, Dependencies, Norms and Internal Dynamics". They're looking at the way coalitions change, in groups of agents represented using dependence networks.
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