sf_bbox: sf bbox

In sfheaders: Converts Between R Objects and Simple Feature Objects

sf bbox

Description

Calculates the bounding box of coordinates. This does not read the "bbox" attribute, it re-calculates the bounding box from the geometry coordinates

Usage

sf_bbox(obj, x = NULL, y = NULL)

Arguments

obj	matrix, data.frame, sfg, sfc or sf object.
x	x geometry column
y	y geometry column

Examples

## data.frame
df <- data.frame(
 id1 = c(1,1,1,1,1,1,1,1,2,2,2,2)
 , id2 = c(1,1,1,1,2,2,2,2,1,1,1,1)
 , x = c(0,0,1,1,1,1,2,2,3,4,4,3)
 , y = c(0,1,1,0,1,2,2,1,3,3,4,4)
)

sf_bbox( obj = df[, c("x","y")] )
sf_bbox( obj = df, x = "x", y = "y" )

## sfg objects
pt <- sfg_point(obj = df[1, ], x = "x", y = "y", z = "id1")
mpt <- sfg_multipoint(obj = df, x = "x", y = "y")
ls <- sfg_linestring(obj = df, x = "x", y = "y")
mls <- sfg_multilinestring(obj = df, x = "x", y = "y")
p <- sfg_polygon(obj = df, x = "x" , y = "y")
mp <- sfg_multipolygon(obj = df, x = "x", y = "y", close = FALSE )

sf_bbox( pt )
sf_bbox( mpt )
sf_bbox( ls )
sf_bbox( mls )
sf_bbox( p )
sf_bbox( mp )

## sfc objects
pt <- sfc_point(obj = df, x = "x", y = "y", z = "id1")
mpt <- sfc_multipoint(obj = df, x = "x", y = "y", multipoint_id = "id1")
ls <- sfc_linestring(obj = df, x = "x", y = "y", linestring_id = "id1")
mls <- sfc_multilinestring(obj = df, x = "x", y = "y", multilinestring_id = "id1")
p <- sfc_polygon(
  obj = df
  , x = "x"
  , y = "y"
  , polygon_id = "id1"
  , linestring_id = "id2"
  , close = FALSE
  )
mp <- sfc_multipolygon(
  obj = df
  , x = "x"
  , y = "y"
  , multipolygon_id = "id1"
  , linestring_id = "id2"
  , close = FALSE
  )

sf_bbox( pt )
sf_bbox( mpt )
sf_bbox( ls )
sf_bbox( mls )
sf_bbox( p )
sf_bbox( mp )

## sf objects
pt <- sf_point(obj = df, x = "x", y = "y", z = "id1")
mpt <- sf_multipoint(obj = df, x = "x", y = "y", multipoint_id = "id1")
ls <- sf_linestring(obj = df, x = "x", y = "y", linestring_id = "id1")
mls <- sf_multilinestring(obj = df, x = "x", y = "y", multilinestring_id = "id1")
p <- sf_polygon(
  obj = df
  , x = "x"
  , y = "y"
  , polygon_id = "id1"
  , linestring_id = "id2"
  , close = FALSE
  )
mp <- sf_multipolygon(
  obj = df
  , x = "x"
  , y = "y"
  , multipolygon_id = "id1"
  , linestring_id = "id2"
  , close = FALSE
  )

sf_bbox( pt )
sf_bbox( mpt )
sf_bbox( ls )
sf_bbox( mls )
sf_bbox( p )
sf_bbox( mp )

## you can use it to update a bounding-box if it gets corrupted
attr( mpt, "bbox" ) <- c(1:5)
mpt ## incorrect values
attr( mpt, "bbox" ) <- sf_bbox( mpt )
mpt ## back to correct values

sfheaders documentation built on May 29, 2024, 1:36 a.m.