point.in.poly: Point and Polygon Intersect

Description

Intersects point and polygon feature classes and adds polygon attributes to points

If duplicate argument is TRUE and more than one polygon intersection occurs, points will be duplicated (new row added) and all attributes joined. However, if duplicate is FALSE, with duplicate intersections, a new column for each unique intersecting polygon will be returned and the points will not be duplicated. For example, if a point intersect three polygons, three new columns will be added representing the polygons ID.

Usage

point.in.poly(x, y, sp = TRUE, duplicate = TRUE, ...)

Arguments

sp SpatialPointsDataFrame or SpatialPoints or sf point object

sp SpatialPolygonsDataFrame or sf polygon object

(TRUE/FALSE) Return an sp class object, else returns sf class object

duplicate

(TRUE/FALSE) Return duplicated features with more than one polygon intersection

...

Additional arguments passed to sf::st_join

Value

A SpatialPointsDataFrame or sf

Examples

Run this code

# NOT RUN {
 #### Simple one-to-one feature overlay. 
 require(sp)
   data(meuse)
   coordinates(meuse) = ~x+y
   meuse@data$test.na <- NA
 
   sr1=Polygons(list(Polygon(cbind(c(180114, 180553, 181127, 181477, 181294,  
     181007, 180409, 180162, 180114), c(332349, 332057, 332342, 333250, 333558,  
     333676, 332618, 332413, 332349)))),'10')
   sr2=Polygons(list(Polygon(cbind(c(180042, 180545, 180553, 180314, 179955, 179142,  
     179437, 179524, 179979, 180042), c(332373, 332026, 331426, 330889, 330683, 
     331133, 331623, 332152, 332357, 332373)))),'20')
   sr3=Polygons(list(Polygon(cbind(c(179110, 179907, 180433, 180712, 180752, 180329, 
     179875, 179668, 179572, 179269, 178879, 178600, 178544, 179046, 179110),
     c(331086, 330620, 330494, 330265, 330075, 330233, 330336, 330004, 
     329783, 329665, 329720, 329933, 330478, 331062, 331086)))),'30')
   sr4=Polygons(list(Polygon(cbind(c(180304, 180403,179632,179420,180304),
     c(332791, 333204, 333635, 333058, 332791)))),'40')
   sr=SpatialPolygons(list(sr1,sr2,sr3,sr4))
   polys=SpatialPolygonsDataFrame(sr, data.frame(row.names=c('10','20','30','40'), 
                                  PIDS=1:4, y=runif(4)))
   polys@data$pid <- polys@data$PIDS + 100 
 
 plot(polys)
   plot(meuse, pch=19, add=TRUE)  
   
 # Point in polygon overlay  
 pts.poly <-  point.in.poly(meuse, polys)
   head(pts.poly@data)
 
 # Count points in each polygon
 tapply(pts.poly$cadmium, pts.poly$pid, FUN=length)    
   
 #### Complex many-to-one feature overlay. 
 require(sf)
 p <- sf::st_polygon(list(rbind(c(0,0), c(1,0), c(1,1), c(0,1), c(0,0))))
 polys <- sf::st_sf(sf::st_sfc(p, p + c(.8, .2), p + c(.2, .8)))
 pts <- sf::st_sf(sf::st_sample(polys, size=100))
 
 # Duplicates points for each new polygon, no attributes so returns IDs for features    
 pts.poly.dup <-  point.in.poly(pts, polys)
   head(pts.poly.dup@data)
   
# }
# NOT RUN {
 # **** Should throw error due to lack of attributes ****  
   pts.poly <- point.in.poly(pts, polys, duplicate = FALSE) 
# }
# NOT RUN {
 
 # Coerce to sp class objects
 x <- as(pts, "Spatial")
   x <- SpatialPointsDataFrame(x, data.frame(IDS=1:nrow(x), pty=runif(nrow(x))))
 y <- as(polys, "Spatial")
   y <- SpatialPolygonsDataFrame(y, data.frame(IDS=1:nrow(y), py=runif(nrow(y))))
 
 # Returns point attributes with column for each unique polygon   
 pts.poly <- point.in.poly(x, y, duplicate = FALSE)
   head(pts.poly@data)  
   
 # Duplicates points for each new polygon, joins all attributes  
 pts.poly.dup <-  point.in.poly(x, y)
   head(pts.poly.dup@data)  
 
 # Count points in each polygon
 tapply(pts.poly.dup$IDS.x, pts.poly.dup$IDS.y, FUN=length)      

# }

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