topic Re: Select points based on minimum connection lines in Geoprocessing Questions

Select points based on minimum connection lines

LanoYado — Mon, 03 Oct 2016 17:27:35 GMT

I am using Model Builder and I have two layers; point and line. I want to select (and then create a point layer of them) those points that have less connections with other points.

For instant, point # 6 is connected to 5 points (# 11, 16, 20, 47, & 19) through 5 lines. Among these five points, # 47 is the one I want to find it since it has only 2 connections with others (# 6 & # 54), the rest have more lines connected to (#19 connected to 3 lines, # 11 connected to 4 lines, #16 connected to 3 lines, #20 connected to 3 lines).

Note that I already calculated (created a field) the number of lines connected to each point using spatial join.

Any way to use in ModelBuilder?

Re: Select points based on minimum connection lines

DanPatterson_Retired — Mon, 03 Oct 2016 17:38:28 GMT

add the XY coordinates to the polyline shapefile using the first and last point option

Add Geometry Attributes—Help | ArcGIS for Desktop

Then you can try summarizing by one of the coordinates or a pair. Given your current pattern where there is unlikely to be no duplicate X or Y values, unless they are the start or end, this should simplify things.

One tip might be to one step further....

Calculate the start and end X and Y values as per usual.
add two new fields and determine the minimum X and Y per line start-end. This willl account for a point in one line being the end in another
summarize one and/or more of the fields in the usual way to get a count of the replication of the coordinates

There are other ways... for example, relates (using rounded truncated coordinates as text etc). or exporting the point coordinates and doing a lexicographic sort (by x, then Y) and then do a rolling difference to count the spacing between difference indices (requires numpy)

Re: Select points based on minimum connection lines

LanoYado — Mon, 03 Oct 2016 17:51:55 GMT

Thanks Dan, I will try with your first way since it looks like easier to me.

Re: Select points based on minimum connection lines

ChrisDonohue__GISP — Mon, 03 Oct 2016 18:32:44 GMT

(scratch this - just realized in re-reading the post that you already did this part)

Chris Donohue, GISP

Re: Select points based on minimum connection lines

LanoYado — Mon, 03 Oct 2016 18:40:42 GMT

Thank you Chris and yes, I have calculated the lines connected to each point using spatial join but the problem is how can I select among these points the one with less connections.

Re: Select points based on minimum connection lines

ChrisDonohue__GISP — Mon, 03 Oct 2016 18:53:36 GMT

How about Select (Analysis) ArcGIS Help (10.2, 10.2.1, and 10.2.2) . Click on the SQL button to the right of "Expression (optional)" to enter your selection criteria.

Chris Donohue, GISP

Re: Select points based on minimum connection lines

LanoYado — Mon, 03 Oct 2016 19:08:05 GMT

That works perfectly. Can we generalize it to ask and select the one with minimum connections? in this example, I just say Join_Count=2. How can we select in general to say:

Join_Count= minimum one (2 in this case)?

Re: Select points based on minimum connection lines

LanoYado — Mon, 03 Oct 2016 20:11:06 GMT

I created the condition using 'get value' with 'statistics summary' but the value can not be read by "select" tool.

Re: Select points based on minimum connection lines

ChrisDonohue__GISP — Mon, 03 Oct 2016 20:28:45 GMT

I was just doing the same thing and ran into the same issue. The Select will work with a hard-coded value (like 1), but doesn't seem to accept Value or its various permutations (like %Value%). Odd.

Chris Donohue, GISP

Re: Select points based on minimum connection lines

ChrisDonohue__GISP — Mon, 03 Oct 2016 20:40:59 GMT

By the way, if you are familiar with Python, you may want to consider doing the process with it instead of Modelbuilder. I believe in Python one has access to a Minimum function, which would save the whole workaround one has to do in Modelbuilder to accomplish the same thing.

Chris Donohue, GISP

Re: Select points based on minimum connection lines

DanPatterson_Retired — Fri, 10 Dec 2021 22:23:59 GMT

min is a built-in

>>> some_stuff = [8,2,5]
>>> min(some_stuff)‍‍

explore as Chris suggests

>>> dir(__builtins__)
['....snip ...'enumerate', 'eval', 'exec', 'exit', 'filter', 'float', 
'format', 'frozenset', 'getattr', 'globals', 'hasattr', 'hash', 'help',
 'hex', 'id', 'input', 'int', 'isinstance', 'issubclass', 'iter', 'len', 
'license', 'list', 'locals', 'map', 'max', 'memoryview', 'min', 'next',
 'object', 'oct', 'open', 'ord', 'pow', 'print', 'property', 'quit', 
'range', 'repr', 'reversed', 'round', 'set', 'setattr', 'slice', 'sorted',
 'staticmethod', 'str', 'sum', 'super', 'tuple', 'type', 'vars', 'zip']‍‍‍‍‍‍‍‍

Re: Select points based on minimum connection lines

ChrisDonohue__GISP — Mon, 03 Oct 2016 20:54:40 GMT

Got it to work.

Not exactly sure why it didn't work before, but after I closed ArcCatalog and reopened it, then reopened the Model and redid the expression, it now works. I also undid the Parameters, but that seemed to have no effect.

Chris Donohue, GISP

Re: Select points based on minimum connection lines

LanoYado — Mon, 03 Oct 2016 21:10:07 GMT

Still not working with me. I know Python is better and faster but I can not switch to it until I can finish my current work with model builder, hopefully soon.

Re: Select points based on minimum connection lines

LanoYado — Mon, 03 Oct 2016 21:19:46 GMT

What type of data should I choose for "get value"?

Re: Select points based on minimum connection lines

ChrisDonohue__GISP — Mon, 03 Oct 2016 21:30:38 GMT

I went with the default, which is "String". Though the field it is checking is a Double precision, but it still worked anyway. (Maybe it has built in casting? Not sure)

I'd check the properties of the field you are running the Get Field Value against and match its properties, if possible. There seems to be String and Long available as choices, but not the others.

Chris Donohue, GISP

Re: Select points based on minimum connection lines

XanderBakker — Tue, 04 Oct 2016 12:33:52 GMT

It would be cool to throw some python code at it (I would never consider ModelBuilder for something like this). Just a small questions. What to do in the case of point 20? It has two connected points that only have connections to one other point (30 and 37). Which one should be taken?

Re: Select points based on minimum connection lines

LanoYado — Tue, 04 Oct 2016 13:46:25 GMT

That is a good question Xander, in that case and for my work, it takes one of them randomly since they have the same weight of connection.

Re: Select points based on minimum connection lines

AbdullahAnter — Wed, 05 Oct 2016 02:39:34 GMT

Genius,Dan