Skip to contents

Computes the maximum inscribed circle of a geometry

Source: R/ddbs_ops_unary.R
ddbs_maximum_inscribed_circle.Rd

Returns the largest circle that fits inside the input geometry. The result is derived from a struct containing the circle's center point, the nearest point on the geometry boundary to that center, and the circle's radius.

Usage

ddbs_maximum_inscribed_circle(
  x,
  geom = "center",
  tolerance = NULL,
  conn = NULL,
  name = NULL,
  mode = NULL,
  overwrite = FALSE,
  quiet = FALSE
)

Arguments

x

Input spatial data. Can be:

  • A duckspatial_df object (lazy spatial data frame via dbplyr)

  • An sf object

  • A tbl_lazy from dbplyr

  • A character string naming a table/view in conn

Data is returned from this object.

geom

a character string specifying which component of the inscribed circle to return. Must be one of "center" (default) or "nearest". "center" returns the center point of the maximum inscribed circle; "nearest" returns the closest point on the geometry boundary to that center.

tolerance

a numeric value specifying the tolerance used when computing the inscribed circle. If NULL (default), tolerance is computed automatically as max(width, height) / 1000.

conn

A connection object to a DuckDB database. If NULL, the function runs on a temporary DuckDB database.

name

A character string of length one specifying the name of the table, or a character string of length two specifying the schema and table names. If NULL (the default), no table is written and the result is returned as a duckspatial_df or sf object, depending on mode

mode

Character. Controls the return type. Options:

  • "duckspatial" (default): Lazy spatial data frame backed by dbplyr/DuckDB

  • "sf": Eagerly collected sf object (uses memory)

Can be set globally via ddbs_options(mode = "...") or per-function via this argument. Per-function overrides global setting.

overwrite

Boolean. whether to overwrite the existing table if it exists. Defaults to FALSE. This argument is ignored when name is NULL.

quiet

A logical value. If TRUE, suppresses any informational messages. Defaults to FALSE.

Value

Depends on the mode argument (or global preference set by ddbs_options):

  • duckspatial (default): A duckspatial_df (lazy spatial data frame) backed by dbplyr/DuckDB.

  • sf: An eagerly collected object in R memory, that will return the same data type as the sf equivalent (e.g. sf or units vector).

When name is provided, the result is also written as a table or view in DuckDB and the function returns TRUE (invisibly).

Examples

if (FALSE) { # \dontrun{
## load package
library(duckspatial)

## read data
argentina_ddbs <- ddbs_open_dataset(
  system.file("spatial/argentina.geojson",
  package = "duckspatial")
)

## return the center point of the maximum inscribed circle
ddbs_maximum_inscribed_circle(argentina_ddbs)

## return the nearest boundary point instead
ddbs_maximum_inscribed_circle(argentina_ddbs, geom = "nearest")

## use a custom tolerance
ddbs_maximum_inscribed_circle(argentina_ddbs, tolerance = 0.01)

## without a connection
ddbs_maximum_inscribed_circle(argentina_ddbs)
} # }