fortify.Spat: Fortify Spat* Objects

In tidyterra: 'tidyverse' Methods and 'ggplot2' Helpers for 'terra' Objects

Fortify ⁠Spat*⁠ Objects

Description

Fortify SpatRaster and SpatVector objects to data frames. This provide native compatibility with ggplot2::ggplot().

Note that these methods are now implemented as a wrapper of tidy.Spat methods.

Usage

## S3 method for class 'SpatRaster'
fortify(
  model,
  data,
  ...,
  .name_repair = c("unique", "check_unique", "universal", "minimal", "unique_quiet",
    "universal_quiet"),
  maxcell = terra::ncell(model) * 1.1,
  pivot = FALSE
)

## S3 method for class 'SpatVector'
fortify(model, data, ...)

## S3 method for class 'SpatGraticule'
fortify(model, data, ...)

## S3 method for class 'SpatExtent'
fortify(model, data, ..., crs = "")

Arguments

model	A SpatRaster created with terra::rast(), a SpatVector created with terra::vect(), a SpatGraticule (see terra::graticule()) or a SpatExtent (see terra::ext()).
data	Not used by this method.
...	Ignored by these methods.
.name_repair	Treatment of problematic column names: "minimal": No name repair or checks, beyond basic existence, "unique": Make sure names are unique and not empty, "check_unique": (default value), no name repair, but check they are unique, "universal": Make the names unique and syntactic "unique_quiet": Same as "unique", but "quiet" "universal_quiet": Same as "universal", but "quiet" a function: apply custom name repair (e.g., .name_repair = make.names for names in the style of base R). A purrr-style anonymous function, see rlang::as_function() This argument is passed on as repair to vctrs::vec_as_names(). See there for more details on these terms and the strategies used to enforce them.
maxcell	positive integer. Maximum number of cells to use for the plot.
pivot	Logical. When TRUE the SpatRaster would be provided on long format. When FALSE (the default) it would be provided as a data frame with a column for each layer. See Details.
crs	Input potentially including or representing a CRS. It could be a sf/sfc object, a SpatRaster/SpatVector object, a crs object from sf::st_crs(), a character (for example a proj4 string) or a integer (representing an EPSG code).

Value

fortify.SpatVector(), fortify.SpatGraticule() and fortify.SpatExtent() return a sf object.

fortify.SpatRaster() returns a tibble. See Methods.

Methods

Implementation of the generic ggplot2::fortify() method.

SpatRaster

Return a tibble than can be used with ⁠ggplot2::geom_*⁠ like ggplot2::geom_point(), ggplot2::geom_raster(), etc.

The resulting tibble includes the coordinates on the columns ⁠x, y⁠. The values of each layer are included as additional columns named as per the name of the layer on the SpatRaster.

The CRS of the SpatRaster can be retrieved with attr(fortifiedSpatRaster, "crs").

It is possible to convert the fortified object onto a SpatRaster again with as_spatraster().

When pivot = TRUE the SpatRaster is fortified in a "long" format (see tidyr::pivot_longer()). The fortified object would have the following columns:

• ⁠x,y⁠: Coordinates (center) of the cell on the corresponding CRS.

• lyr: Indicating the name of the SpatRaster layer of value.

• value: The value of the SpatRaster in the corresponding lyr.

This option may be useful when using several ⁠geom_*⁠ and for faceting, see Examples.

SpatVector, SpatGraticule and SpatExtent

Return a sf object than can be used with ggplot2::geom_sf().

See Also

tidy.Spat, sf::st_as_sf(), as_tibble.Spat, as_spatraster(), ggplot2::fortify().

Other ggplot2 utils: autoplot.Spat, geom_spat_contour, geom_spatraster(), geom_spatraster_rgb(), ggspatvector, stat_spat_coordinates()

Other ggplot2 methods: autoplot.Spat

Coercing objects: as_coordinates(), as_sf(), as_spatraster(), as_spatvector(), as_tibble.Spat, tidy.Spat

Examples

# Demonstrate the use with ggplot2
library(ggplot2)

# Get a SpatRaster
r <- system.file("extdata/volcano2.tif", package = "tidyterra") |>
  terra::rast() |>
  terra::project("EPSG:4326")

# You can now use a SpatRaster with any geom
ggplot(r, maxcell = 50) +
  geom_histogram(aes(x = elevation),
    bins = 20, fill = "lightblue",
    color = "black"
  )

# For SpatVector, SpatGraticule and SpatExtent you can use now geom_sf()

# Create a SpatVector
extfile <- system.file("extdata/cyl.gpkg", package = "tidyterra")
cyl <- terra::vect(extfile)

class(cyl)

ggplot(cyl) +
  geom_sf()

# SpatGraticule
g <- terra::graticule(60, 30, crs = "+proj=robin")

class(g)

ggplot(g) +
  geom_sf()

# SpatExtent
ex <- terra::ext(cyl)

class(ex)

ggplot(ex, crs = cyl) +
  geom_sf(fill = "red", alpha = 0.3) +
  geom_sf(data = cyl, fill = NA)

tidyterra documentation built on March 11, 2026, 9:08 a.m.