poleInaccessibility: Find a binary pole of inaccessibility

In hutilscpp: Miscellaneous Functions in C++

Find a binary pole of inaccessibility

Description

Find a binary pole of inaccessibility

Usage

poleInaccessibility2(
  x = NULL,
  y = NULL,
  DT = NULL,
  x_range = NULL,
  y_range = NULL,
  copy_DT = TRUE
)

poleInaccessibility3(
  x = NULL,
  y = NULL,
  DT = NULL,
  x_range = NULL,
  y_range = NULL,
  copy_DT = TRUE,
  test_both = TRUE
)

Arguments

x, y	Coordinates.
DT	A data.table containing LONGITUDE and LATITUDE to define the x and y coordinates.
x_range, y_range	Numeric vectors of length-2; the range of x and y. Use this rather than the default when the 'vicinity' of x,y is different from the minimum closed rectangle covering the points.
copy_DT	(logical, default: TRUE) Run copy on DT before proceeding. If FALSE, DT have additional columns updated by reference.
test_both	(logical, default: TRUE) For 3, test both stretching vertically then horizontally and horizontally then vertically.

Value

poleInaccessibility2

A named vector containing the xmin, xmax and ymin, ymax coordinates of the largest rectangle of width an integer power of two that is empty.

poleInaccessibility3

Starting with the rectangle formed by poleInaccessibility2, the rectangle formed by stretching it out vertically and horizontally until the edges intersect the points x,y

Examples

library(data.table)
library(hutils)
# A square with a 10 by 10 square of the northeast corner removed
x <- runif(1e4, 0, 100)
y <- runif(1e4, 0, 100)
DT <- data.table(x, y)
# remove the NE corner
DT_NE <- DT[implies(x > 90, y < 89)]
DT_NE[, poleInaccessibility2(x, y)]
DT_NE[, poleInaccessibility3(x, y)]

hutilscpp documentation built on April 4, 2025, 12:42 a.m.