transform_coord: Transform spatial coordinates to another projection
In ggOceanMaps: Plot Data on Oceanographic Maps using 'ggplot2'

transform_coord

R Documentation

Transform spatial coordinates to another projection

Description

Transforms spatial coordinates from original projection (decimal degrees assumed) to another projection.

Usage

transform_coord(
  x = NULL,
  lon = NULL,
  lat = NULL,
  new.names = "auto",
  rotate = FALSE,
  proj.in = 4326,
  proj.out = NULL,
  verbose = FALSE,
  bind = FALSE,
  na = "ignore"
)

Arguments

`x`	Data frame to be transformed. Can be omitted if numeric vectors are assigned to `lon` and `lat`.
`lon`, `lat`	Either a name of the longitude and latitude columns in `x` or a numeric vector containing longitude and latitude coordinates. Use `NULL` to guess the longitude and/or latitude columns in `x`.
`new.names`	Character vector of length 2 specifying the names of transformed longitude and latitude columns, respectively. Alternatively `NULL`, which returns column names from `x` or "auto", which uses `NULL` if `bind = FALSE` and `c("lon.proj", "lat.proj")` if `bind = TRUE`.
`rotate`	Logical indicating whether the projected maps should be rotated to point towards the pole relative to the mid-longitude limit.
`proj.in`	The original `CRS`. If `NULL`, the projection is taken from `x`. `x` must be a spatial object in that case.
`proj.out`	Character. Either `NULL`, `CRS` the coordinates should be transformed to or a name of shapefiles in `shapefile_list`. If `NULL`, the output projection will be automatically determined from data. This option requires decimal degrees as input option.
`verbose`	Logical indicating whether information about the projection should be returned as message. Set to `FALSE` to make the function silent.
`bind`	logical. Should only transformed coordinates be returned (`FALSE`, default) or should x be returned with transformed coordinates (`TRUE`)?
`na`	character specifying the NA action for missing coordinates. The "ignore" option ignores the coordinates and returns NAs to transformed coordinates. The "remove" option removes missing values from `x` returning a message while doing it. Any other character argument will trigger `na.fail` stopping the function in case of missing coordinates.

Details

If x is specified, the function guesses longitude and latitude columns from x by default.

Value

Returns a data frame with transformed spatial coordinates.

Author(s)

Mikko Vihtakari

Examples

# Coordinates are automatically transformed to the pre-made shapefile
# projections:
x <- data.frame(lon = c(-150, 150), lat = c(60, 90))
transform_coord(x)
transform_coord(x, bind = TRUE)

x <- data.frame(lon = c(-150, 150), lat = c(20, 50))
transform_coord(x, bind = TRUE) # no transformation required.

ggOceanMaps documentation built on May 29, 2024, 5:36 a.m.