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update attribute data based on spatial location

DavidMcDermott

I have a large number of polygons. Each polygon has 1 or more points within. I would like to populate a field in the point data with data from a polygon field based on spatial location. I know I could use spatial join but I don't want a new feature, I just want to update the information in the point feature.

P.S. I this would work the other way would it would be great.

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JoeBorgione

How many is "a large number" ? You could iterively select each polygon, perform a spatial selection of the points based on the selected polygon and update the point attributes accordingly. I'm sure there is a way for Python to cursor through the same sort of process.

DavidMcDermott

By large, I mean 3000 to 6000 hence why selecting each one is not an option. I am working with postcode centroids (points) inside postcode polygons. I create territories by entering delivery numbers into the polygons, then dissolving them based on that number. I then need to transfer the numbers to points inside the polygons. These points contain more detained address information which are then expored to a database. Thanks for the input though.

TimothyHales

This is a little out there, but you could convert you polygon to raster, and then use the Add Surface Information tool to add the raster values to the points.

JoeBorgione

By large, I mean 3000 to 6000 hence why selecting each one is not an option. I am working with postcode centroids (points) inside postcode polygons. I create territories by entering delivery numbers into the polygons, then dissolving them based on that number. I then need to transfer the numbers to points inside the polygons. These points contain more detained address information which are then expored to a database. Thanks for the input though.

Yep! 3K-6k qualifies as a large number! Even if there was a common field to relate to, calculating the values you are after would be an arduous chore... Maybe the spatial join option is looking better?

Best of luck with this.

DavidMcDermott

Thales007 - Thank you for your input, unfortunately your solution would not work in this case. The information in each polygon (and therefore point) is amended on a weekly, sometimes daily basis. Converting it to raster would just mean more work.

jborgion - I have used a spatial join in the past but it creates a new feature which is not ideal (see above). However, I have given it some thought, and while I am no expert, I feel using modelbuilder to create a workflow would help speed things up. Tell me what you think:

Manually enter delivery information then - Dissolve feature based on delivery number > spatial join (SJ) polygons to points > Select points by location within dissolve feature (to speed things up) > join SJ feature to points based on postcode > field calculator data into relevant fields > Remove join > delete SJ feature.

I'm not even sure model builder can do that but I would like to think it can.

JoeBorgione

There is only one way to find out; try it...

RichardFairhurst

Thales007 - Thank you for your input, unfortunately your solution would not work in this case. The information in each polygon (and therefore point) is amended on a weekly, sometimes daily basis. Converting it to raster would just mean more work.

jborgion - I have used a spatial join in the past but it creates a new feature which is not ideal (see above). However, I have given it some thought, and while I am no expert, I feel using modelbuilder to create a workflow would help speed things up. Tell me what you think:

Manually enter delivery information then - Dissolve feature based on delivery number > spatial join (SJ) polygons to points > Select points by location within dissolve feature (to speed things up) > join SJ feature to points based on postcode > field calculator data into relevant fields > Remove join > delete SJ feature.

I'm not even sure model builder can do that but I would like to think it can.

Creating a temporary output in a model is a standard process, so the fact that you are using tools that create a new feature class that you ultimately want preserved in a permanent feature class is no reason to avoid using a tool. My question is will every point you have only be located within a single Dissolved Polygon? If so ModelBuilder definitely can definitely do the job.

If that is the case, you just need to use the JOIN ONE TO ONE option with the Spatial Join and make the Point the Target features and the Dissolved Polygons the Join Features. That output will have a single record for each point with the attributes from the one matchin Dissolved Polyton. You can perform a standard attribute join of the Spatial Join output to your points on the Point ObjectID to the Sparial Join Target_FID and do the data transfer. The main trick in ModelBuilder is that you have to use the Create Feature Layer tool on the Point Feature Class first before you can do an attribute join of your points to the Spatial Join output.

Anyway, based on myu experience with doing most of my models based on this kind of workflow, here are the tools I would normally use:

Dissove - Dissolve the Polygons and make sure any attributes you need to transfer to the points are in the summary.

Spatial Join - Points are the Target feature and Dissolved polygons are the Join feature using the JOIN ONE TO ONE option.

Add Attribute Index - Index the TARGET_FID field in the Spatial Join Output to improve attribute join performance.

Create Featuer Layer - Create a feature Layer of the Points.

Join - perform an attribute Join of the Point Feature Layer (ObjectID) to the Spatial Join output (Target_FID).

(Optionally) Select By Attribute - Select where JOIN_FID > -1 if you only want to modify points that actually fell within a polygon or skip this step if you don;t care.

Field Calculator - Use this tool to transfer the information. Use it as many times as you need to fill in all of the data derived from the Dissolved Polygons to the points.

Remove Join - Remove the Attribute Join

Delete - Delete the Spatial Join output.

DavidMcDermott

jborgion - I certainly will when I get to work Monday Morning and I will inform you.

rfairhur24 - Thanks for the input, you solution has given me some great ideas to streamline the process and improve accuracy. I will try it Monday morning.

JohnSandberg

I'm trying to do essentially the same thing - update multiple fields in an existing Feature Class with attributes from other Feature Classes, based on spatial relationships (overlay). All without creating new output datasets. Seems like this should be possible...any suggestions?

RichardFairhurst

I'm trying to do essentially the same thing - update multiple fields in an existing Feature Class with attributes from other Feature Classes, based on spatial relationships (overlay). All without creating new output datasets. Seems like this should be possible...any suggestions?

There are ways, but you either have to do it one record at a time (Attribute Transfer tool in an edit session) or you have to write a custom cursor pair in Python or ArcObjects, which normally performs much slower than the method I have outlined involving creating new output datasets. Overall Geoprocessing tools are definitely oriented to creating new outputs and not to modifying existing outputs. In ModelBuilder you do not have to retain the intermediate datasets if you don't want to (they will be cleaned up when the process finishes), but they still must be created at least temporarily. If you manage to retain a link back to your original dataset through the process I outlined, you can join the output to your original input and calculate the results back to it, but that only works if the final output has a one-to-one relationship to your original input.

Creating and using relationships (spatial and attributes) is practically 90% of my work. If anyone has a more direct route to acheiving the correct ends I am interested, but these processes have worked for me over the years and been the easiest for me to debug.

DarrenWiens2

Depending on the size of your datasets and amount of RAM available on your system, you could potentially save some time writing/deleting by taking advantage of the in-memory workspace.

SamCoggins1

If you want to join the polygon information to the points I have a Python script that will do that for you. Let me know.

DavidMcDermott

Hi,

Sorry for my absence. I went with rfairhur24 solution and it worked perfectly. With our new 64-bit PC's the process is very swift within modelbuilder. The in-memory option sounds very appealing not only for this model but other that I have built. I am currently looking to convert some of my tools into python scripts/tools to make them easier to share.

David

KathrynLeBlanc

Do you still have that script Sam? I have to do something similar and I don't know much about scripts

LiseTremblay

My strategy is to make sure there are unique ID's in the feature you want to update, even if you have to make a temp attribute. run an intersect. join the new feature to the old one using the unique ID and calculate the attribute based on the joined attribute that has the correct info cause it was intersected. For poly to poly intersects, I convert the one I need to update to a point first again... unique ID is the key.

CynthiaRoush2

I'm not using models, but this answer pointed me to the procedure I needed to fill a field based on a spatial relationship with another feature class: Spatial Join, Join that output to the original, Calculate Field, remove Join, delete Spatial Join output. Thanks!

AndyMaracini

worked perfectly, I swear I had a mental block for this most basic GIS operation.

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