Spatial grid map

This layer tool is very similar to the spatial grid display, with a couple of exceptions:

• It cannot be used to set the values of model components
• If used with a component in a hexagonal grid, the cells will be shown in a 'brickwork' pattern corresponding to the centres of the hexagons.

This tool may also be slower than the spatial grid display, since a more complex image scaling operation is required to get the grid to the exact scale to match other components.

In: Contents >> Running models >> Working with helpers >> Layer tool

Polygon map

This layer tool is generally similar to the polygon helper, and is set up in a similar way. The differences are as follows:

• It can be set to redraw the polygon outlines at each display interval, to cope with models in which polygons appear and disappear, or change shape
• It cannot be used to set values of model components
• The value for the colour is selected first. If this is from a hexagonal grid submodel, there is no need to provide vertex coordinates -- the helper generates the hexagon outlines itself.
• The properties dialogue allows a stipple pattern to be chosen for filling the polygons. This allows lower layers to be partially seen through them.

This tool is faster than the old polygon helper with large numbers of polygons.

In: Contents >> Running models >> Working with helpers >> Layer tool

2-D Shape Layer

This layer tool is similar to the stand-alone 3-D shape viewer, but displays 2-D shapes in a layer rather than projected 3-D shapes. Whereas one instance of the 3-D shape viewer can display sets of shapes corresponding to several sets of model valriables, each instance of the shape viewer layer only displays a set for one group of model variables. If multiple sets of shapes are required, each one can be added in the same view as a separate layer.

The shapes that can be added are circle, ellipse or line. Each has a separate submenu entry for adding it, so once it is added, the modeller is prompted for the information that enables the display to be set up. X and Y co-ordinates are set from components in the model, or fixed numeric values can be entered in an input field. If a model component is chosen for the colour of a shape, the colour legend editor appears in order to record how the model values will be converted into colours for the corresponding components.

Spatial input layer

This layer helper allows spatial input to be sent to a model during execution. When it is added as a layer, the modeller is requested to select three variable parameters from the model. These must be scalar with numerical units.

The first two of these will hold the X and Y coordinates of a position in the field of view of the layer tool. They are not changed until the modeller clicks or drags within the tool. At that point they will be continually updated with the pointer position within the layer tool until the unclick. The final variable is set to zero at any time when a click or drag is not in progress. It is set to 1 when a click occurs and is incremented by 1 whenever the pointer coordinates change during a drag. This is so the model can keep track of the speed or duration of the drag. It is set to zero again on the unclick.

This tool does not itself display anything within the layer helper area. Normally it would be added to a layer tool which is also showing a spatial grid covering the area in which the coordinates could be expected to fall, so the tool could be 'zoomed to fit' resulting in the input pointer layer also extending over the right range of coordinates. If there is no actual grid to display, the area covered by the input tool could be set by adding four 'line' layers, each with a single line corresponding to one side of the rectangle containing the desired input coordinates. These coordinates could be entered directly to the layer tool as numbers, or got from model variables.

Background photo

This is not really a visualization tool at all -- it just allows an image to be displayed as a background to the layers. Generally the image will be some form of map that corresponds to the data in the model. Because the pixel pitch of the image may not correspond to the position data in the model, the properties dialogue allows an offset and scale to be set for the image display. Thus the tool also allows the whole layer display to be annotated with small images.

When the tool is selected, a file selection dialogue appears for choosing the image file, which immediately displays. Its offset and scale are then adjusted via its properties dialogue. To change the image, delete the layer and add a new one.

In: Contents >> Running models >> Working with helpers >> Layer tool

Show moving individuals

If a model includes a group of submodel instances representing mobile individuals, it may be desirable to display them on a map background using icons. That is what this layer tool is for. It can draw a lot of copies of an icon representing an individual at positions specified by model data. It can also vary the size and orientation of the icons according to data from the model.

The image data file

In order to do this, the icon must be expressed as a series of canvas drawing commands in the Tk language. Tk is the standard graphics extension for scripting languages including Tcl, Perl, Python and Ruby. An example file to draw the ants in the image on the Layer tool page is included in Simile's examples directory, and the images for Simile's population channels are also encoded in this way. These files typically have the extension .cnv. It is hoped to offer a Paintbox-style drawing tool for creating images in this format in the near future.

The file consists of a series of commands to draw the icon on a canvas referred to as $c. This will cause it to be drawn in the layer display when sourced by this tool's code. If the ability to rotate the icon is to be used, then only canvas objects that can be drawn at any angle should be included, i.e., avoid arcs and ovals (unless circular) and rectangles. As well as drawing commands, the file should include an instruction to set the hotspot -- this is the point in the image that will be positioned on the map point given by the model data, as a pair of integers, e.g.,

set hotspot {100 150}

Similarly the scale should be set, i,e., the number of canvas units of the drawing commands corresponding to one unit of map space. A large value will mean the image is drawn small, and is useful for precision because positions and line thicknesses in the image file must be integers.

set scale 10

It should also set the axis direction, in which the image as drawn by the canvas commands appears to be facing. This can either be a compass point (ne, sw, etc), an hour on the clock face (6h, 9h, etc) or a number which will be treated as the number of radians the axis lies anticlockwise from the x axis. e.g., these three forms are valid and equivalent:

set axis n

set axis 12h

set axis 1.57

Setting up the tool

When the layer is selected, a file selection dialogue appears for choosing the image file. Once the file is selected, its contents are loaded into the helper setup, so the file is not consulted again -- if the image is altered, the layer must be deleted and re-created to display the new version of the image. Now you will be prompted to click on model components for the x and y coordinates of the individuals' positions on the map. These have to be supplied. You will be prompted to click on two more model components to specify the size and orientation of the individuals. If you do not wish the icons to be changed in size, just click on one of the components you have already clicked on at this point, and the size will not be altered. The value of the orientation component can be a number, which is interpreted as the number of radians anticlockwise from the x axis which the image will be shown facing. Alternatively it can be a member one of the enumerated types used to index the neighbour directions in the special-purpose submodels, in which case the image will be drawn facing in that direction. In either case, if the value of the direction component is the same as the axis direction in the model file, the icon is drawn unrotated. If no rotation is to be done, select a component that has already been selected for x or y position as the rotation.

In: Contents >> Running models >> Working with helpers >> Layer tool

Other visualization tools : Event sounds helper

The motivation behind Simile's visualization tools is to provide the modeller with a continuous, immediate understanding of what the model is doing. Sometimes the best way to do this is with sounds rather than graphics. With the addition of discrete events to the modelling language, we realized that their instantaneous nature does not lend itself to the kind of graphical displays that work for continuous values. 

So we created an event logger that also produces a sound each time a selected event occurs. Add an instance of this tool in the standard way, selecting 'Event sounds' from the list of helper titles. Now after clicking '+' in the helper window's toolbar, you can select a discrete event component in your model, and a sound file to play each time the event occurs. The window will show a 'ticker bar' which will move across the screen right to left, with a vertical line added each time the event occurs. Hovering over the lines will pop up the exact time and magnitude of the occurrence they represent.

Also, the sound will be played each time the event occurs. If your event has a numeric magnitude, then the volume of the sound will be determined by where each event's magnitude falls between the min and max values given for the event. Sound files in WAV format will play on all platforms -- files in other formats (e.g., mp3) may play on your particular platform but are not guaranteed to play on all.

If the chosen event occurs very frequently, or if it is in a simple model that runs very fast, the sounds may overrun each other producing unpleasant noise. In this case you can use the 'limit updates/sec' feature to slow the model execution down to the point where the sounds can be heard separately.

Polygon diagram

This tool enables a dataset to be displayed as the colours of polygonal areas on a map. It can be used either where vector data for an actual map is available (either in the model, or in a separate file), or where an area is represented as some regular set of shapes whose vertices can be calculated by the model, e.g. hexagonal tiling.

A lot of the functionality of the polygon helper, including scrolling and zooming, working with the colour legend, and using it to edit model parameter values, is exactly the same as for the grid helper. However, the graphics of the polygon helper are not quite as fast, so you are more likely to need the 'freeze display' and 'manual update' features.

Loading co-ordinates from file

If you choose this option you will get a file selector to locate the data for the coordinates. If you choose a file with the extension .dxf, Simile will attempt to load it as a DXF file, and will then colour the polygons in the order in which they are defined in the file. Otherwise, Simile currently expects the file to contain all the X coordinates in nested list form, followed by all the Y coordinates. This is not particularly convenient, so we should add the option to set the coordinates from file using the table data dialogue too.

Loading co-ordinates from model

Of course you can put fixed parameters in the model and load them using the table data dialogue, then use them to set the boundaries of the polygons. If you choose this option, you will be asked to select model elements representing the X and Y coordinates of the polygon vertices. These elements should have two-dimensional data arrays, with the outer index being the number of the polygon whose border they define, and the inner index being the number of the vertex around that polygon. There should be the same number and arrangement of X and Y coordinates.

The usual way to get the coordinates is to have a submodel for the vertices inside the submodel representing the polygons. This should be a per-record submodel if different polygons have different numbers of vertices. Put fixed parameters for Xs and Ys inside the vertices submodel. 

In: Contents >> Running models >> Working with helpers

Standard helpers : edit sketch graph function

If your model contains equations that use the graph function, their function can be altered while the model is running. The tool for doing this appears as a helper, although it does not display values from the model or directly set them.

The helper is located in the "Standard tools" subdirectory menu and is called "Edit sketch graph function". Create an instance of the helper and click on the model component whose function you wish to alter. You will then see the same sketch graph editing window as when you originally created the sketch graph. You are able to drag the sketch line as well as edit the axis values and change the settings that control how the sketch is interpreted.

Any changes you make to the sketch graph function will take effect as soon as you hit the 'OK' button, but the helper will stay up until you delete it, allowing further changes to be made at any point. Note that the edited function will not be saved with the model. If you save the model after editing the sketch using the helper, it will keep the original version of the function. To change this you must go back to the equation dialogue and hit the "Graph" button.

The Data Logger tool does not display model data, but records it in files for later analysis with statistical tools. There are other ways of doing this:

• The Table Helper can save its contents as a .csv file, but has poor performance with large data sets
• The Snapshot tool can record values as the model runs, but only handles one variable, and needs setting up every time the model is run

By contrast, the Data Logger can handle any size of data set that is usable within Simile, and can log multiple variables, either in separate files or as columns in a single file. Since it is a standard helper, many instances can be added for different groups of values, and the setup can be saved as part of a general helper layout.

Using the tool

The tool's canvas will be blank when it is first added. To log a variable, hit the + button and click the variable on the model diagram. It will be listed within its hierarchy of submodels, with a '-' button ffor its removal. Hit + again to add more variables. The rightmost button in the helper's toolbar switches between saving separate files for each variable (named by the variable's caption) and a single file (log.csv) with each variable in its own column.

Saved file format

The helper will not save any data until you select a folder in which to save it. Click the toolbar button with the folder icon and navigate to the desired location. Now a line is written to the log file(s) at each display point as the model executes. The files are in .csv format with the time points stored in the left hand column. If the values being saved are arrays, they will be written as series of alternating indices and values, with each series enclosed in curly brackets, i.e., the same format as data popups or directly-entered file parameters.

The file is closed when the model is paused, and opened for appending more data when it is restarted. When the model is first run after a reset or rebuild, the file will be opened for writing, so the previous contents will be overwritten unless they have been moved.

As of Simile v6.9, it is also possible to log model data to a database -- either a file in some Excel-compatible format (.xls, .xlsx etc) or a MySQL database. To log to a database file, simply select it from the file dialogue. To log to a MySQL database, cancel the file dialogue and this will cause the database specification dialogue to appear. Here you enter the hostname, username, password and name of the MySQL database.

When logging to a database, each component being logged will have values put in its own column in the database. If logging an array component, there will be a separate column for each element in the array, named value/n where value is the name of the component and n is the index of the element. (value/n1/n2/... for multi-dimensional arrays). The values will be written to a table called 'Run 0' until the model is reset, after which new tables called 'Run 1', 'Run 2' etc will be created for data values from subsequent runs.