Spatial join: Joining all attributes to a polygon layer IF they correspond with the highest value of one of the attributes

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04-08-2016 08:03 AM
JessieFoest
New Contributor II

Dear ArcGIS community,

I am trying to add attribute information of a soil type polygon layer to a biodiversity (output) polygon layer, where both polygon layers are different (and thus, there are different soil types in each biodiversity polygon). I only want to include the soil type that is most common in the biodiversity polygons (i.e. largest area) Thus, I thought, I would preform a Union, then calculate the area of each section and put this largest area and the soil type of this area in centroids. Then I wanted to perform a Spatial join of these centroids to the original biodiversity layer, but in a way that ONLY the soil types would be added if that soil type is most common based on the area I calculated before.

I have, however not found a way to do this (i.e. make the output soil type attribute dependent on if the corresponding area is larger than the other soil type areas within the biodiversity polygon).

What would be a way to approach this?

Thank you so much in advance, it really means a lot!

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11 Replies
WesMiller
Regular Contributor III

Could you add a field to both and calculate the areas on both then do your spatial join then do a selection area1 > area2 or area2 > area1

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JessieFoest
New Contributor II

Sorry, I do not understand your answer entirely? Could you please clarify it a bit further?

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MervynLotter
Regular Contributor

Hi Jessie

I would convert my soil data to raster, and then use *Zonal statistics as

table tool* to and Majority statistics type to sect the most common soil

type in each polygon.

Regards

Mervyn

JessieFoest
New Contributor II

Thank you, I think this did the trick! I will check in the morning and mark the question as answered

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JessieFoest
New Contributor II

Zonal statistics as table worked! Only, I get 18500 out of my 87.346 overlapping polygons? Is there a limit to the length of the Zonal Statistics as table tool, and can I work around this?

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MervynLotter
Regular Contributor

Hi Jessie

I have run this tool on a lot more polygons. I suspect something else my be

at play, as Dan suggests, perhaps overlapping polygons.

I gather you would have linked the zonal stats table back to your polygon

data. Select those with zero values and run zonal stats tool just on these

to see if perhaps now the balance of the units can be populated with soil

data.

Cheers

Mervyn

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DanPatterson_Retired
MVP Esteemed Contributor

Curtis posted a couple of links here https://community.esri.com/message/519722#comment-519722

and the blog reference is here https://blogs.esri.com/esri/arcgis/2013/11/26/new-spatial-analyst-supplemental-tools-v1-3/

designed to handle overlaps

JessieFoest
New Contributor II

Thank you all so much for the help. I've tried the new zonal statistics as table 2 tool, and run a 'Find overlapping features' analysis which did not find any overlapping polygons.

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DanPatterson_Retired
MVP Esteemed Contributor

Your earlier thread said you had overlapping zones.  Is this not the case?

I hope you aren't confusing features in a featureclass to zones in a raster.  You can have 1000 discrete polygons in a featureclass consisting of 10 classes... no overlaps... when converted to raster you will have 10 classes and all the apparent discrete zones have vanished since in a raster, it is the class that is important not their spatial position.  Regiongroup is the tool to use when you convert vector polygons to raster to represent different spatial areas.  Regiongroup assigns a unique value to each contiguous zone/area.  It is equivalent to doing a multipart to singlepart operation in vector world.

So.. is there any overlap in the features that were converted to polygon?

You can alter the settings...within reason... that Arcmap uses for some options.  You can access them from

Advanced ArcMap Settings utility—Help | ArcGIS for Desktop folder location if you have admin privileges on your machine.

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