Calculating percentage of slope and aspect for each parcel

[JohnnyHarley232]

Hello! I have a task where I thousands of parcels and calculate slope and divide the raster into low, medium, and high slope. Then from there, give the percentage of each category for each parcel. I have successfully calculated slope (degrees) for my dataset and converted the raster in polygons and then performed a Tabular Intersection tool to determine percentage of each category for each parcel. 

Now the hard part. I need to determine the direction of aspect for each parcel. is there a way to calculate what the majority aspect is for a zone or boundary? 

[DavidPike]

Zonal Statistics as Table (Spatial Analyst)—ArcGIS Pro | Documentation should be pretty painless, use the MAJORITY option.

[JohnnyHarley232]

Hi David, unfortunately, when calculating Aspect.. Zonal Statistics by Table doesnt bring up Majority as an option when calculating statistics!

[DanPatterson]

Zonal Statistics as Table (Spatial Analyst)—ArcGIS Pro | Documentation

If the value input is floating point, the Majority, Minority, and Variety statistics are not available for calculation.

Majority, Minority and Variety are characteristics of nonparametric data.  Think of it as counts of data and since interval/ratio data have a fineness of scale that isn't inherent in classed or ordinal data, because of it.

Class the data into groups as David suggests and use that or produce those values

I would caution against using "mean" or other such statistical measures since circular data (eg aspect) requires special calculations for those (Google statistics for directional data or similar terms

[DavidPike]

ah of course.  Probably Reclassify (Spatial Analyst)—ArcGIS Pro | Documentation into your N,NE.. bands.  Hopefully with your symbology set as that renderer, the tool will populate the class breaks for you also.

Surface Aspect (3D Analyst)—ArcGIS Pro | Documentation might also do the leg-work for you.

[RyanDeBruyn]

This post might be of some help for reference.   See the CalcZonalMeanAspect sample.

Calculate mean aspect for polygons