The network dump (also called netstate output or netstate dump) was the first output capability that was implemented in SUMO. It contains detailed information for each edge, each vehicle and each simulation step. Due to the high level of detail it is very flexible but often requires additional programming to parse and filter the information that is actually desired. The Simulation/Output/FCDOutput has a similar level of detail but does not group vehicles based on their edge.
Instantiating within the Simulation#
<output> <netstate-dump value="<FILE>" /> </output>
<FILE> is the name of the file the output will be written to. Any other file with this name will be overwritten, the destination folder must exist.
The network dump is a xml-file containing for each time step every edge of the network with every lane of this edge with all vehicles on this lane. For each vehicle, its name, speed and position on its respecitve lane are written. A raw dump-file looks like this:
<netstate> <timestep time="<TIME_STEP>"> <edge id="<EDGE_ID>"> <lane id="<LANE_ID>"> <vehicle id="<VEHICLE_ID>" pos="<VEH_POSITION>" speed="<VEH_SPEED>"/> ... more vehicles if any on this lane ... </lane> ... more lanes if the edge possesses more ... ... optional persons and containers if currently active on that edge <person id="<ID>" pos="<OFFSET_FROM_EDGE_BEGIN>" speed="<SPEED>"/> ... <container id="<ID>" pos="<OFFSET_FROM_EDGE_BEGIN>" speed="<SPEED>"/> ... </edge> ... more edges .... </timestep> ... the next timestep ... </netstate>
If persons or containers are transported within a vehicle, they are written as child elements of that vehicle rather than as child elements of the edge.
The meanings of the written values are given in the following table.
|time||(simulation) seconds||The time step described by the values within this timestep-element|
|id||id||The id of the edge/lane/vehicle|
|pos||m||The position of the vehicle at the lane within the described time step (distance of the front bumper from the start of the lane)|
|speed||m/s||The speed of the vehicle within the described time step|
|posLat||m||Offset from the center of the lane (only when using the sublane model)|
|personNumber||#||number of persons in the vehicle (not in MESO)|
|containerNumber||#||number of containers in the vehicle (not in MESO)|
|stage||string||description of the current stage (only for persons and containers)|
The option --netstate-dump.precision <INT> controls the number of significant digits when writing positions and speeds to the output file. The option --netstate-dump.empty-edges <BOOL> controls whether edges without vehicles are included in the output.
As you may imagine, this output is very verbose. Its main disadvantage is the size of the generated file. It's very easy to generate files that are several GB large within some minutes. It is of course possible to write some nice tools that parse the file (using a SAX-parser) and generate some meaningful information, but we do not know anyone who has made this. Another problem is that the simulation's execution speed of course breaks down when such an amount of data must be written.
Normally, all lanes are written, even if there is no vehicle on them. You can change this behaviour using the boolean switch --netstate-dump.empty-edges. In this case, only those edges and lanes will be written that contain vehicles.