topic Re: FIND DISTANCES BETWEEN POWER POLES in Python Questions

FIND DISTANCES BETWEEN POWER POLES

nimitz — Wed, 30 Nov 2016 18:42:27 GMT

Hi all,

I have a Personal GEODB that contains Point FC (POLES), Line FC (OVERHEAD TRANSMISSION LINE). I'm trying to use the Point-Distance tool in Toolbox, but it's giving me funky results. I'm on 10.2.1 and Pro.

Ideally I'd like to have a new column(or a new table if that won't work) that shows the distance between 2 power poles, ie. POLE205-POLE206 - 250'. Or something along those lines.

When I run the tool, it's giving me 54,000 records, a lot more than I'd imagine for 854 transmission poles!

Many thanks,

Re: FIND DISTANCES BETWEEN POWER POLES

DanPatterson_Retired — Wed, 30 Nov 2016 19:14:13 GMT

funky normally means that you aren't using projected data and are getting values returned in decimal degrees. So you have several options including setting your data frame to a projected coordinate system and returning geometry measures in he coordinate system of the data frame... or physically projecting your data to a new file and doing all your work in the planar world... or funky may mean you are expecting one unit and getting another (ie feet versus meters etc) Of course an example of what you got and what your expect would provide the final clue to the possible solutions.

Re: FIND DISTANCES BETWEEN POWER POLES

BlakeTerhune — Wed, 30 Nov 2016 19:27:48 GMT

When using the Point Distance tool, are you specifying the search_radius parameter? If you don't, it gives you the distance to all other points; which seems like it's not what you're after. It sounds like maybe you only want to look at other poles that are connected by a segment of transmission line. What are the rules by which you name your poles and how do your transmission line features connect them?

Re: FIND DISTANCES BETWEEN POWER POLES

nimitz — Wed, 30 Nov 2016 19:43:15 GMT

NAD83 CA STATE PLANE ZNII US SURVEY FOOT.

I just realized it's probably calculating the distances from EACH POLE TO EVERY OTHER POLE. sheesh!

Re: FIND DISTANCES BETWEEN POWER POLES

nimitz — Wed, 30 Nov 2016 22:02:46 GMT

Ok, it looks like after I put in a radius of 500', it's more "normal" now. The question is, "What fields can I use from the derived table to spatially join to my existing POWER POLE FC? It seems like the OBJECTID, INPUT_FID, NEAR_FID are random numbers, right?

Re: FIND DISTANCES BETWEEN POWER POLES

DanPatterson_Retired — Wed, 30 Nov 2016 22:15:55 GMT

Look at the visual in the lin that Blake sent Point Distance—Help | ArcGIS for Desktop it shows what the relationship is between the features and the near feature

Re: FIND DISTANCES BETWEEN POWER POLES

nimitz — Wed, 30 Nov 2016 23:41:24 GMT

I've looked at the help for point distance. I'm afraid that those OBJECTID's that were generated in the new table DON'T correspond to the ORIGINAL OBJECTID's from my POLE file. I did a join based on the OBJECTID's, and the calculated distances are different (by a 100' or so) from what I actually measure.

hmmm...maybe I have to refine the radius to something a little smaller? 400' or so?

Re: FIND DISTANCES BETWEEN POWER POLES

DarrenWiens2 — Wed, 30 Nov 2016 23:48:07 GMT

Look at the picture in Dan's link:

and read the description:

INPUT_FID: The feature ID of the input features
NEAR_FID: The feature ID of the near features

OBJECTID is the autonumber ID for the output table - it doesn't necessarily match with anything in the poles feature class.

Re: FIND DISTANCES BETWEEN POWER POLES

BlakeTerhune — Sat, 11 Dec 2021 08:44:13 GMT

ObjectID is not random; it's a unique, sequential number automatically assigned by a ArcGIS to create a primary key field. the FID in the tool's output is referring to the ObjectID field.

If you want have it show one of your key fields instead, you'll have to do a table join on ObjectID. I got tired of doing this so I made a script that will generate a near table that automatically includes a key field of my choice. *Disclaimer: I made some adjustments to the code just now to make it more generic and have not tested*

import arcpy
import os

try:
    # Set local variables
    working_gdb = r"C:\temp\TEMP.gdb"
    ## IN and NEAR features can be the same
    in_fc = "FirstFeatureClass"
    in_fc_key = "MyKeyFieldName"  ## Assumes Long Integer data type
    in_fc_path = os.path.join(working_gdb, in_fc)
    near_fc = "SecondFeatureClass"
    near_fc_key = "MyKeyFieldName"  ## Assumes Long Integer data type
    near_fc_path = os.path.join(working_gdb, near_fc)
    search_radius = "25 Feet"

    # Create near table and make as TableView
    neartable_inmem = os.path.join("in_memory", "neartable_inmem")
    arcpy.GenerateNearTable_analysis(
        in_fc_path,  ## in_features
        near_fc_path,  ## near_features
        neartable_inmem,  ## out_table
        search_radius,  ## search_radius
        "NO_LOCATION",  ## location
        "NO_ANGLE",  ## angle
        "ALL",  ## closest
        "0",  ## closest_count
        "PLANAR"  ## method
    )
    if arcpy.GetMessages(1):
        print arcpy.GetMessages(1)  ## Write arcpy warning
    arcpy.MakeTableView_management(neartable_inmem, "neartable_view")
    print "Near table created"

    # Add key fields to near table
    in_key = "IN_{}".format(near_fc_key)
    arcpy.AddField_management(
        "neartable_view",  ## in_table
        in_key,  ## field_name
        "LONG",  ## field_type
    )
    if arcpy.GetMessages(1):
        print arcpy.GetMessages(1)  ## Write arcpy warning
    near_key = "NEAR_{}".format(near_fc_key)
    arcpy.AddField_management(
        "neartable_view",  ## in_table
        near_key,  ## field_name
        "LONG",  ## field_type
    )
    if arcpy.GetMessages(1):
        print arcpy.GetMessages(1)  ## Write arcpy warning
    print "New key fields added"

    # Join and calc in_key field
    arcpy.AddJoin_management(
        "neartable_view",  ## in_layer_or_view
        "IN_FID",  ## in_field
        in_fc_path,  ## join_table
        "OBJECTID",  ## join_field
        "KEEP_COMMON"  ## join_type
    )
    if arcpy.GetMessages(1):
        print arcpy.GetMessages(1)  ## Write arcpy warning
    arcpy.CalculateField_management(
        "neartable_view",  ## in_table
        in_key,  ## field
        "!{}!".format(in_fc_key),  ## expression
        "PYTHON_9.3"  ## expression_type
    )
    if arcpy.GetMessages(1):
        print arcpy.GetMessages(1)  ## Write arcpy warning
    arcpy.RemoveJoin_management("neartable_view")
    if arcpy.GetMessages(1):
        print arcpy.GetMessages(1)  ## Write arcpy warning
    print "{} field populated".format(in_key)

    # Join and calc near_key
    arcpy.AddJoin_management(
        "neartable_view",  ## in_layer_or_view
        "NEAR_FID",  ## in_field
        near_fc_path,  ## join_table
        "OBJECTID",  ## join_field
        "KEEP_COMMON"  ## join_type
    )
    if arcpy.GetMessages(1):
        print arcpy.GetMessages(1)  ## Write arcpy warning
    arcpy.CalculateField_management(
        "neartable_view",  ## in_table
        near_key,  ## field
        "!{}!".format(near_fc_key),  ## expression
        "PYTHON_9.3"  ## expression_type
    )
    if arcpy.GetMessages(1):
        print arcpy.GetMessages(1)  ## Write arcpy warning
    arcpy.RemoveJoin_management("neartable_view")
    if arcpy.GetMessages(1):
        print arcpy.GetMessages(1)  ## Write arcpy warning
    print "{} field populated".format(near_key)

    # Export final near table
    out_near_table_path = os.path.join(
        working_gdb,
        "{}_nearKey".format(arcpy.ValidateTableName(in_fc, working_gdb))
    )
    arcpy.CopyRows_management(
        "neartable_view",  ## in_rows
        out_near_table_path  ## out_table
    )
    if arcpy.GetMessages(1):
        print arcpy.GetMessages(1)  ## Write arcpy warning

    print "Near table output at {}".format(out_near_table_path)

except Exception as err:
    print err
    ## If there was an ArcPy error, write all of the messages returned by the last tool
    if arcpy.GetMessages(2):
        print arcpy.GetMessages()

finally:
    # Cleanup
    arcpy.Delete_management("in_memory")‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: FIND DISTANCES BETWEEN POWER POLES

BlakeTerhune — Thu, 01 Dec 2016 00:14:37 GMT

If there is a specific rule about how you want to measure the distance to a feature other than "if it's nearby", then you might need to do some extra logic to filter out the unnecessary measurements.

Re: FIND DISTANCES BETWEEN POWER POLES

nimitz — Thu, 01 Dec 2016 14:50:07 GMT

So, I have the INPUT_FID and NEAR_ID fields. However, if there are 5 INPUT_FID with the number 1, that is not going to be useful in doing a join to the original GEODB.

Would this be a good time to create a GEOMETRIC network with my TRANSMISSION LINE file?

Re: FIND DISTANCES BETWEEN POWER POLES

BlakeTerhune — Thu, 01 Dec 2016 16:53:53 GMT

The Point Distance tool is doing exactly what it is supposed to. I think you're trying to make it do something it's not meant to. That's why I asked if you have some specific rules about how your poles are connected. Please describe the topological interaction between poles and transmission lines. In other words: how would a computer know that it needs to measure the distance to one pole but not another?

Re: FIND DISTANCES BETWEEN POWER POLES

nimitz — Thu, 01 Dec 2016 17:07:34 GMT

Blake,

Topologically speaking, I have no rules for the TRANSMISSION LINE FC. I did a quick import from AutoCAD - so it's a safe bet I/we never set any topological rules at all. Having said that, the POLE FC has no rules either.

I can refine the parameters a little bit more and run the tool again, but my suspicion is (and I think yours is), I'm going to have to "clean" up the TRANSMISSION LINE file (ie snap the line together for runs). Which I've been doing here and there for the past month, but I've dreaded.

Many thanks for the help.

Re: FIND DISTANCES BETWEEN POWER POLES

BlakeTerhune — Thu, 01 Dec 2016 17:34:15 GMT

I didn't mean that you actually needed to have topology rules created, just describe to us how the two are supposed to exist. You probably only need to snap them if it would help some custom process to clean it up. The Point Distance tool won't care if there's a transmission line snapped to the pole.

Re: FIND DISTANCES BETWEEN POWER POLES

ChrisDonohue__GISP — Thu, 01 Dec 2016 18:00:59 GMT

If the transmission towers are coincident with the lines and the lines are all connected without gaps (I know, probably too much to ask with CAD data sometimes), one workflow would be to split the transmission line by the tower points, add attribute fields to the split lines for start and end, then use a Join to add the tower information to the lines. The result will be a line feature class attributed with the tower ID for each end of the line that you can then read the distances off of.

Here's a similar question that was posted on GeoNet recently. The full process is described in detail at the end of the thread.

Distinguishing lines that connect different type of points

You will also need this:

Split Line at Point—Data Management toolbox | ArcGIS for Desktop

The one catch is that I don't know if ArcGIS Pro has all this.

Chris Donohue, GISP