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Extract a single layer/attribute

Source: R/pull-Spat.R
pull.Spat.Rd

pull() is similar to $ on a data frame. It is mostly useful because it looks nicer in pipes and can optionally name the output.

You can extract the geographic coordinates of a SpatRaster. Use pull(.data, x, xy = TRUE). x and y are reserved names on terra, since they refer to the geographic coordinates of the layer.

See Examples and section About layer names on as_tibble.Spat().

Usage

# S3 method for class 'SpatRaster'
pull(.data, var = -1, name = NULL, ...)

# S3 method for class 'SpatVector'
pull(.data, var = -1, name = NULL, ...)

Arguments

.data

A SpatRaster created with terra::rast() or a SpatVector created with terra::vect().

var

A variable specified as:

  • a literal layer/attribute name.

  • a positive integer, giving the position counting from the left.

  • a negative integer, giving the position counting from the right.

The default returns the last layer/attribute (on the assumption that's the column you've created most recently).

This argument is taken by expression and supports quasiquotation (you can unquote column names and column locations).

name

An optional parameter that specifies the column to be used as names for a named vector. Specified in a similar manner as var.

...

Arguments passed to as_tibble.SpatRaster() or as_tibble.SpatVector() methods.

Value

A vector with the same number of cells/geometries as .data.

On SpatRaster objects, note that the default (na.rm = FALSE) removes empty cells, so you may need to pass (na.rm = FALSE) to .... See terra::as.data.frame().

terra equivalent

terra::values().

Methods

Implementation of the generic dplyr::pull() methods. Each method first coerces the Spat* object to a tibble (see as_tibble.Spat) and then applies dplyr::pull() to the tibble.

SpatRaster

When passing na.rm = TRUE to ..., only cells with a value other than NA are extracted. See terra::as.data.frame().

If xy = TRUE is passed to ..., two columns named x and y (corresponding to the geographic coordinates of each cell) are available in positions 1 and 2. Therefore, pull(.data, 1) and pull(.data, 1, xy = TRUE) return different results.

SpatVector

When passing geom = "WKT" or geom = "HEX" to ..., the geometry of the SpatVector can be extracted with var = geometry. Similarly, when using geom = "XY", the coordinates can be extracted with var = x or var = y. See the options in terra::as.data.frame().

See also

dplyr::pull().

Other dplyr verbs that operate on columns: glimpse.Spat, mutate.Spat, relocate.Spat, rename.Spat, select.Spat

Examples


library(terra)
f <- system.file("extdata/cyl_tile.tif", package = "tidyterra")
r <- rast(f)

# Extract the second layer.
r |>
  pull(2) |>
  head()
#> [1] 229 235 229 229 239 153

# With `xy`, the first two columns are `x` (longitude) and `y` (latitude).

r |>
  pull(2, xy = TRUE) |>
  head()
#> [1] 5370160 5370160 5370160 5370160 5370160 5370160

# With renaming

r |>
  mutate(cat = cut(cyl_tile_3, c(0, 100, 300))) |>
  pull(cyl_tile_3, name = cat) |>
  head()
#> (100,300] (100,300] (100,300] (100,300] (100,300] (100,300] 
#>       206       224       206       206       233       169