SPEED Lab Mobile iOS Applications

Mobile iOS Application: Spatial Population Ecological and Epidemiological Dynamics Simulator, Version 1.0

A newer version of this app is currently available on the iTunes App Store for the iOS platform which runs on Apple's iPhone, iPod Touch, and iPad platforms, and allows users to interactively explore the dynamics of spatial simulation models. An Android app will hopefully be available later (when it is, info will be linked to back on the parent Mobile Apps page). Here is a link to information about the current version.

Notice: there is currently a bug in Version 1.0 of the application running under iOS 5: if you immediately try to switch to the lattice view when starting the app, it doesn't run correctly. Going to the "model" and choosing a model there before running seems to make the simulations run properly (if you want to run the default model, first choose a different one and then re-choose the original). The current version of the app fixes this behavior.

Below is more information about the models included in Version 1.0 of the application.

Dispersal 2: Population model with local dispersal at distance 1 or 2, and long-distance dispersal.
SIRS: Spatial epidemiological model.
Vaccinated communities: Epidemiological model with varying vaccination levels among different communities.

User interface

Here is some basic information about the user interface for the application.

Lattice view

You can use pinch-to-zoom with the lattice view to magnify it, and drag the view around if you are zoomed in.
Some models support drawing in the lattice. Tap and hold on the lattice screen, to draw in the lattice. The "brush" menu (under the "more" tab on the iPhone) lets you choose which state/color you are drawing, and the brush size.
Tap the "Save" button to save a snapshot of the image to your device's Photos library.
Tap "Run" to begin the simulation; the "Run" button then becomes a "Pause" button to stop the simulation.
Tap "Reset" to reinitialize the model and start a fresh simulation.

Plot view

The top row of buttons (Keep, Show All, Hide Old, and Clear Old) let you keep and manage plots of multiple simulation runs within the same figure window. Because the models are stochastic, if you run the same model multiple times, you will see somewhat different results. If you tap "Keep", the current simulation's plot data will be saved. Tapping "Show All" or "Hide Old" determines whether previously Kept plots are displayed. "Clear old" removes all Kept plots.
Tap the "Save" button to save a snapshot of the current plot to your device's Photos library.
The "Run" and "Reset" buttons from the Lattice view are also shown in the Plot view.

Parameters view

This view displays parameters specific to the current model. Some of the parameters take effect right away (such as birth rates, infection rates, etc.), while others take effect when the model is reset (such as initial infections, etc.).

Model view

This view lets you select from among the models included with the application. The text box beneath the model selector is scrollable, and includes a brief description of the model.

Settings view

This view (accessed from within the "More" tab on an iPhone) lets you set parameters common to all of the models within the application, such as the size of the lattice, how often to update Plots, etc. The upper range of the y-axis for Plots can also be set here; note that it is given in terms of numbers rather than proportions, so e.g. on a 50x50 lattice, setting ymax to 2500 means that the top of the Plot corresponds to 100% of the sites occupied or infected.

Brush

Here you can control which state will be drawn when you tap-and-hold in the Lattice view, as well as the brush size for drawing.

Known issues/problems

Devices running versions of iOS earlier than 4.0 may not correctly save images to the Photo library.
On devices running versions of iOS earlier than 4.1 or 4.2, the parameters/settings sliders may behave a bit strangely. When you move one slider, sliders above it may readjust themselves. Setting the sliders from the bottom up should allow you to put them all where you want them. (We're not sure exactly which versions this affects, as we don't currently have access to a device running 4.1.)
The "immunity clustering" parameter in the Vaccinated Communities model currently doesn't quite match its description in the corresponding research paper. When clustering is 0, all communities should have identical vaccination levels.