sf_transform_xy: Transform spatial position data

In ggplot2: Create Elegant Data Visualisations Using the Grammar of Graphics

Transform spatial position data

Description

Helper function that can transform spatial position data (pairs of x, y values) among coordinate systems. This is implemented as a thin wrapper around sf::sf_project().

Usage

sf_transform_xy(data, target_crs, source_crs, authority_compliant = FALSE)

Arguments

data	Data frame or list containing numerical columns x and y.
target_crs, source_crs	Target and source coordinate reference systems. If NULL or NA, the data is not transformed.
authority_compliant	logical; TRUE means handle axis order authority compliant (e.g. EPSG:4326 implying x = lat, y = lon), FALSE means use visualisation order (i.e. always x = lon, y = lat). Default is FALSE.

Value

A copy of the input data with x and y replaced by transformed values.

Examples

if (requireNamespace("sf", quietly = TRUE)) {
# location of cities in NC by long (x) and lat (y)
data <- data.frame(
  city = c("Charlotte", "Raleigh", "Greensboro"),
  x =  c(-80.843, -78.639, -79.792),
  y = c(35.227, 35.772, 36.073)
)

# transform to projected coordinates
data_proj <- sf_transform_xy(data, 3347, 4326)
data_proj

# transform back
sf_transform_xy(data_proj, 4326, 3347)
}

ggplot2 documentation built on Oct. 12, 2023, 5:08 p.m.