topic Re: Network analysis in Python in ArcGIS Network Analyst Questions

Network analysis in Python

MatthiasBuehler — Mon, 23 Feb 2015 22:35:05 GMT

Hi,

I'd like to automate the following tasks completely in Python. Can somebody provide me with some introductory code ?

1) Define a street network in a GDB ( actually also create the street features in Python based on other data)

2) Take that street network as the network analysis base

3) Define a start point and end point of a route ( do these points have to be exactly ON the network line ?)

4) Run the analysis

5) Print out in the console how long it would take to walk that distance (at a certain speed)

A very simple example with 3 imaginary streets would be very helpful.

Any input welcome!

Thanks,

Matt

Re: Network analysis in Python

DanPatterson_Retired — Mon, 23 Feb 2015 22:41:20 GMT

have you examined the code snippets in the help files for the process you wish to use? Have you done this manually? If so you can copy the Results window output and generate a shell of a script. Have you tried modelbuilder to generate a workflow ? That can be used to generate a script.

There are some examples of how to do this here:

"You are not allowed to use Modelbuilder": When Instructors need to get smarter and here

"You are not allowed to use Geoprocessing Results... ": The Students get smarter

Re: Network analysis in Python

MelindaMorang — Tue, 24 Feb 2015 17:36:17 GMT

Hello Matthias.

For 1), what do you mean by "define a street network in a GDB"? If you have an existing network dataset, you can easily use it in python for your analysis. However, it is not possible to create a network dataset (meaning define its source features and set up all its properties) in python.

The rest of your steps can definitely be done in python. Check out the code samples on this page: ArcGIS Help (10.2, 10.2.1, and 10.2.2).

There are many code samples like that throughout the Network Analyst tool documentation which should help get you started.

Re: Network analysis in Python

MatthiasBuehler — Tue, 24 Feb 2015 18:57:40 GMT

Hi everyone,

Thanks for the inputs.

Well, I think I have to start at the very beginning with every step individually, but so many questions pop in my mind now. I have some experience in Python, but am just trying to get into arcPy.

[

By 'define a street network in a GDB' I mean:

- Create an empty GDB

- Create a polyline FC

- Fill in the street polylines with their attribution.

But that is just a subtask of my workflow.

]

So what I basically would like to do in one python session :

- define the input streets

- create the street network metadata ('network dataset')

- define e.g. a start and end point by coordinates

- run the simulation

- get the results (e.g. a polyline representing the best path and save it in an other GDB)

- close the session

Is that second step ('create network dataset') not possible to do in python ?

Thanks,

Matt

Re: Network analysis in Python

MelindaMorang — Tue, 24 Feb 2015 19:23:42 GMT

Correct, it's the 'create network dataset' step that is not possible in python.

Why do you need to re-create the network dataset every time? If you just want to solve a route between a different start and end point, you can re-use the network dataset, especially if the points are all within the same geographic area.

Re: Network analysis in Python

MatthiasBuehler — Tue, 24 Feb 2015 19:32:35 GMT

Hi,

I need a different street network every time I run the simulation because it may potentially change every time (design iterations). I need a FULL simulation setup every time.

Can I use Python to set up a GP Tool Model to set the simulation up, instead of running everything purely in Python ?

Thanks,

Matt

Re: Network analysis in Python

MelindaMorang — Tue, 24 Feb 2015 19:40:08 GMT

Oh, I see. Yes, you can use python for every step except the network dataset creation and network dataset property editing. I don't know what you mean by "Can I use Python to set up a GP Tool Model to set the simulation up". It's also not possible to alter network dataset properties in Model Builder. You could possibly use ArcObjects to do that, and then you could call your ArcObjects executable code from within a python script.

If the only thing that's changing are the street features referenced by the network dataset, you might be able to automate the whole thing. Before starting your simulations, you could create your network dataset and get all the attributes and other properties defined. Then, during each run of your simulation, if you edit the street features, you can just run the Build tool on the network dataset so that it incorporates the new edits. If, on the other hand, you actually need to edit the network's attributes or connectivity properties or something, you will not be able to automate that with python.

Have you created a network dataset before? If not, I think it might be best if you run through the network dataset creation tutorial (ArcGIS Help (10.2, 10.2.1, and 10.2.2) ) first before you continue planning your simulation. This will give you some idea of what's involved and put some of my suggestions above into context.

Re: Network analysis in Python

MatthiasBuehler — Tue, 24 Feb 2015 20:41:29 GMT

Hi,

By 'GP Tool Model' I meant using Model Builder.

Yes, I have run through two tutorials that show how to set up a network dataset and run two different simulations (best path, service area).

It's sad to hear this is not possible in Python. I have only heard of ArcObjects, but I am not a programmer, so I think I would fail on this..

But I am pretty sure I will not need to edit the network itself, just swap the whole dataset with a new one before each sim cycle. This could also be done using a 'prepared' scene. The only thing I want to avoid is to have to manually click things, e.g. opening a scene file and click something. I want to trigger 1 script and get the result.

If I could automate that, that could be good already...

Matt

Re: Network analysis in Python

MatthiasBuehler — Fri, 27 Feb 2015 15:20:53 GMT

what would be the possible time frame for this to be implemented ?

any input welcome.

thanks!

Matt

Re: Network analysis in Python

MatthiasBuehler — Wed, 04 Mar 2015 15:23:20 GMT

so this:

ArcGIS Help (10.2, 10.2.1, and 10.2.2)

is NOT what I'd need, right ?

Re: Network analysis in Python

MelindaMorang — Wed, 04 Mar 2015 16:26:30 GMT

The Build Network tool is the final step in network dataset editing or creation. After you've edited the source features or updated the network dataset properties (which has to be done manually), you have to run the Build Network tool in order for those changes to really take effect in the network.

So no, this tool doesn't do everything you want to do, but you will still need this tool as the final step in your procedure.

Re: Network analysis in Python

MatthiasBuehler — Wed, 04 Mar 2015 19:42:20 GMT

Hi Melinda,

thanks for the input.

okay, then back to the question about the timeframe for this to be implemented.

if every other step is possible, that should be too, right ?

please let me know.

matt

Re: Network analysis in Python

MelindaMorang — Wed, 04 Mar 2015 19:52:32 GMT

I wasn't sure what you were referring to when you asked about the timeframe for "this" to be implemented. Are you referring to the ability to create and/or edit network dataset properties in python? If so, I can't answer that question except to say that we have no definitive plans to provide that functionality at this time. We are aware that many users want this functionality, however. It's on our radar.

Re: Network analysis in Python

MatthiasBuehler — Thu, 05 Mar 2015 00:39:26 GMT

hi,

yes, I referred to creating and editing network datasets and their properties in python.

ok, good to see I'm not the only one that would like this.

thanks!

matt

Re: Network analysis in Python

LukeSussex1 — Thu, 22 Oct 2020 00:42:10 GMT

Matthias Buehler‌ did you get anywhere with this?

Melinda Morang‌ Have there been any advancements in the ability to edit network dataset properties such as group connectivity using python? It is something I would like to do.

Thanks,

Luke

Re: Network analysis in Python

MatthiasBuehler3 — Thu, 22 Oct 2020 06:15:53 GMT

Hi Luke,

I haven't heard back, but I also never dove back into this topic. Maybe it's implemented meanwhile, it's been 5 years. 😉

Cheers,

matt

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Re: Network analysis in Python

MelindaMorang — Thu, 22 Oct 2020 15:32:12 GMT

It is not possible to edit network dataset properties in python, and that capability is not planned, either. However, since this was originally posted, it is possible to create a network dataset in python with a pre-defined schema using the Create Network Dataset From Template tool. If you can configure your network dataset manually once so it has the desired properties, you can create a template from it, and then you can automatically re-create this same network with the same properties with different input data (as long as it has the same schema).