A Quick Introduction to the DynaMind GUI¶

The Problem¶

We will model our city as a superblock (i.e. a rectangle) that is further partitioned into smaller city blocks using a grid system. In addition we assume that every grid point has to be connected to the water supply system and want to find an efficient pipe structure to achieve this goal. One solution to this problem is to model the supply system as a connected graph where nodes represent junctions and edges represent streets with possible pipes. For the sake of convenience we consider a minimum spanning tree of this grid graph a sufficient solution to the problem. In the following we will explain step for step how to implement this solution in DynaMind.

Building a workflow¶

First we have to add our superblock. You can find the SuperBlock module in the BlockCity category on the left and can add it to your workflow window via a drag&drop operation. Let us now take a closer look at the module. One important property of a module are the data streams (also views) it operates on.

If you right-click the module and select show data stream you get information about how the module accesses the different data streams that you define (views accessed in module) and the data streams in its scope (module input views). For our module the latter table is currently empty as we did not define any data streams yet. However the upper table is non empty and indicates that we write a data stream named SUPERBLOCK of type Faces which has the attributes height and width of type double, respectively.

The second property is the configuration of a module (accessible via a double-click) that allows one to set module specific parameters. Set the superblock’s height and width to 400 and 600, respectively and apply the changes (press OK).

Next we want to partition our superblock into smaller city blocks. Drag&Drop the CityBlock module into your main window. Furthermore take a look at its property section and change its EdgeName parameter from “STREET” to “EDGES”. Again we take a look at the module data stream section (right-click and select show data stream). Note that the module input views table is again empty and that the views accessed in module table’s SUPERBLOCK row is marked red. This is caused by the reason that a city block module needs to read a superblock but currently does not have any in its scope.

We can solve this problem by connecting the superblock’s out port to the city block’s in port (using drag&drop) to declare a dependency between these modules. In particular this brings data streams defined in preceding modules into the scope of succeeding modules. After connecting the two modules convince yourself that the city block module can now read the superblock by taking a look at its data streams. Note that SUPERBLOCK is now available in the module’s input views section (its scope).

Executing a Workflow¶

At this point it makes sense to visualize our city to check if it suffices our expectations. First we have to execute our workflow by clicking the Run Simulation button in the toolbar. As our model is very basic the results are available immediately and can be inspected. Right-click on the city block, select view data at out port 'city', click add layer, select EDGES and press OK. You can see a visual representation of our abstract city (a grid in our case).

Solution¶

As explained earlier we want to find an efficient pipe structure for our abstract city’s water supply system by calculating a minimum spanning tree. You can find the SpanningTree module inside the Graph category on the left. Add it to your workflow (drop it anywhere) and inspect its data streams. The SpanningTree needs NODES and (weighted) EDGES to calculate the tree (taking a look at a module’s data streams is a good heuristics when specifying workflows with DynaMind). We already defined EDGES previously via the city block module.

To satisfy the need for nodes we add the ExtractNodesFromEdges module (in the Graph category) and connect its in port to the city block module. The last thing we are still missing is the Weight attribute that is essential to the minimum spanning tree calculation. We provide it by adding a AttributeCalculator which is a module that makes it possible to append attributes to defined data streams (category Modules). In particular we first connect its in port to the previously added ExtractNodesFromEdges and its out port to the SpanningTree module. At this point remark the warning about the non-existing attribute Weight in the log section of the window.

We get rid of it by accessing the module’s property section (double-click) and selecting EDGES in its views section. We insert “Weight” into the Attribute field (this is expected by the spanning tree module) and insert an arbitrary constant (42 comes to mind) into the Expression field.

At this point we have modelled the solution via DynaMind and can run a simulation. Before we proceed we get rid of the old simulation result and press the Reset button (the broom) in the toolbar. Then click Run Simulation and select view data at out port 'Layout' to visualize the result (add layer -> select EDGES -> OK). Note that the graph may differ from the screenshots in this tutorial as there are multiple minimum spanning trees for our specific grid graph.

Congratulations, you modelled and solved your first problem with DynaMind!