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I am trying to do something relatively simple but with large shapefiles. I have a shapefile of protected areas in the USA: protected areas

and watershed boundaries: Watershed boundaries

I want to calculate the percentage and proportion of protected areas in each watershed. I want to retain the designation of each protected area as well (i.e., federal, state, etc.)

To do this I started to try to intersect the two shapefiles:

pas <- readOGR(dsn = ".", layer = "PADUS1_4Combined") # protected areas

huc <- readOGR(dsn = ".", layer = "HUC2_USA_PRJ") # hydrologic units (2 digit, USGS)

Checked the CRS

crs(huc)

crs(pas)

crs(huc) CRS arguments: +proj=aea +lat_1=29.5 +lat_2=45.5 +lat_0=23 +lon_0=-96 +x_0=0 +y_0=0 +datum=NAD83 +units=m +no_defs +ellps=GRS80 +towgs84=0,0,0

crs(pas) CRS arguments: +proj=aea +lat_1=29.5 +lat_2=45.5 +lat_0=23 +lon_0=-96 +x_0=0 +y_0=0 +datum=NAD83 +units=m +no_defs +ellps=GRS80 +towgs84=0,0,0

Intersection:

test <- gIntersection(pas, huc)

I get this error:

Error in RGEOSBinTopoFunc(spgeom1, spgeom2, byid, id, drop_lower_td, unaryUnion_if_byid_false, : rgeos_crdMat2LinearRing: linearRing not created

I searched for this error and cannot find anything. I am dealing with a very large dataset here so I am wondering if this is the issue.

Is there a workaround using simple features (sf)?

  • It could be the size of the dataset (you've not said how big it is) or it could be a problem with the geometry of a feature - perhaps a polygon not valid or something. Try it with subsets. Also try sf and see what happens. – Spacedman Apr 3 at 7:12
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It may be there is a problem with your shapefiles which could be cleaned before you attempt the intersection?

Could you try:

library(cleangeo)
huc = clgeo_Clean(huc)

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