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Convert a data.frame or data.table to an simple feature (sf) object

Source: R/fun_as_sf.R
atl_as_sf.Rd

This function converts a data.frame or data.table to a simple feature (sf) object, allowing flexible specification of the x and y coordinate columns. Additional attributes can also be retained in the resulting sf object. There are three options = c("points", "lines", "table").

Usage

atl_as_sf(
  data,
  tag = "tag",
  x = "x",
  y = "y",
  projection = sf::st_crs(32631),
  additional_cols = NULL,
  option = "points"
)

Arguments

data

A data.table or an object convertible to a data.table. The input data containing the coordinates and optional attributes.

tag

A character string representing the name of the column containing the tag ID.

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".

projection

An object of class crs representing the coordinate reference system (CRS) to assign to the resulting sf object. Defaults to EPSG:32631 (WGS 84 / UTM zone 31N).

additional_cols

A character vector specifying additional column names to include in the resulting sf object. Defaults to NULL (no additional columns included).

option

A character string with "points" (default) for returning sf points, "lines" to return sf lines and "table" to return a table with a sf coordinates column.

Value

An sf object containing the specified coordinates as geometry and any included attributes.

Author

Johannes Krietsch

Examples

library(data.table)

# Example data
data <- data.table(
  tag = c("A", "A", "B", "B"),
  x = c(10, 20, 30, 40),
  y = c(50, 60, 70, 80),
  value = c(100, 200, 300, 400)
)

# Convert to sf points with custom CRS and retain the "value" column
sf_points <- atl_as_sf(data,
  x = "x", y = "y", tag = "tag",
  projection = sf::st_crs(4326),
  additional_cols = "value"
)
plot(sf_points)


# Convert to sf lines
sf_lines <- atl_as_sf(data, x = "x", y = "y", tag = "tag", option = "lines")
plot(sf_lines)


# Convert to a data.table with coordinates column
sf_table <- atl_as_sf(data, x = "x", y = "y", tag = "tag", option = "table")
print(sf_table)
#>       tag      geometry
#>    <char>   <sfc_POINT>
#> 1:      A POINT (10 50)
#> 2:      A POINT (20 60)
#> 3:      B POINT (30 70)
#> 4:      B POINT (40 80)