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Create a bounding box with specified aspect ratio and buffer

Source: R/fun_bbox.R
atl_bbox.Rd

This function generates a bounding box for a given geometry with a specified aspect ratio. Additionally, it allows applying a buffer to expand or contract the bounding box.

Usage

atl_bbox(data, x = "x", y = "y", asp = "16:9", buffer = 0)

Arguments

data

An sf or sfc object for which the bounding box is calculated or a data.table with x- and y- coordinates.

x

A character string representing the name of the column containing x-coordinates. Defaults to "x".

y

A character string representing the name of the column containing y-coordinates. Defaults to "y".

asp

A character string specifying the desired aspect ratio in the format "width:height". Default is "16:9", if NULL returns simple bounding box without modifying aspect ratio.

buffer

A numeric value (in meters) specifying the buffer distance to be applied to the bounding box. Positive values expand the bounding box, while negative values shrink it. Default is 0.

Value

A bounding box (bbox), represented as a named vector with xmin, ymin, xmax, and ymax values.

Author

Johannes Krietsch

Examples

# packages
library(tools4watlas)
library(ggplot2)
library(sf)
#> Warning: package 'sf' was built under R version 4.5.3
#> Linking to GEOS 3.14.1, GDAL 3.12.1, PROJ 9.7.1; sf_use_s2() is TRUE

# load example data
data <- data_example

# bounding box based on data
bbox <- atl_bbox(data, buffer = 1000)

# bounding box based on specified coordinates in EPSG:4326
bbox <- data.table(x = c(5.107, 5.330), y = c(53.303, 53.230)) |>
  st_as_sf(coords = c("x", "y"), crs = 4326) |>
  st_transform(crs = 32631) |>
  atl_bbox(buffer = 1000)

# bounding box based on polygon
bbox <- atl_bbox(grienderwaard, buffer = 1000)

# create basemap with bounding box
bm <- atl_create_bm(bbox)

# plot bm with bounding box when bm coordinates are overridden by geom_sf
bm +
  geom_sf(data = grienderwaard, fill = "transparent", color = "firebrick") +
  # set extend again (overwritten by geom_sf)
  coord_sf(
    xlim = c(bbox["xmin"], bbox["xmax"]),
    ylim = c(bbox["ymin"], bbox["ymax"]), expand = FALSE
  )
#> Coordinate system already present.
#> ℹ Adding new coordinate system, which will replace the existing one.