Shift, rotate, and crop a SpatVector or a SpatRaster

shift_and_crop() shifts and rotates a SpatRaster by a specified horizontal distance, then crops it to the extent of a SpatVector that has been similarly transformed.

This function is particularly useful for working with rasters and vectors that span the International Date Line (e.g. the Russian territory).

Usage

shift_and_crop(
  raster,
  vector,
  dx = -45,
  precision = 5,
  overlap_tolerance = 0.1,
  ...
)

Arguments

raster

A SpatRaster object to be shifted, rotated, and cropped.

vector

A SpatVector object to be shifted and rotated.

dx

(optional) A number indicating the amount of the horizontal shift in degrees. Positive values shift to the right, negative values shift to the left (default: -45).

precision

(optional) An integer number specifying the number of decimal digits to use when rounding longitude and latitude coordinates (default: 5).

overlap_tolerance

(optional) A number specifying the tolerance for overlapping geometries when combining vectors. This value controls the allowable error when merging overlapping geometries (default: 0.1).

...

Additional arguments passed to crop().

Value

A SpatRaster object that has been shifted and rotated by the specified amount in degrees, then cropped to the extent of the provided vector.

See also

Other terra functions: shift_and_rotate()

Examples

# Set the Environment -----

library(curl)
library(dplyr)
library(geodata)
library(ggplot2)
library(terra)
library(tidyterra)
#> 
#> Attaching package: ‘tidyterra’
#> The following object is masked from ‘package:stats’:
#> 
#>     filter

plot_vector <- function(vector) {
  plot <-
    vector |>
    ggplot() +
    geom_spatvector(fill = "#3243A6", color = "white")

  print(plot)
}

plot_raster <- function(raster) {
  plot <-
    ggplot() +
    geom_spatraster(data = raster) +
    scale_fill_continuous(
      palette = c("#072359", "#3243A6", "#9483AF"),
      na.value = "white"
    ) +
    labs(fill = NULL)

  print(plot)
}

# Define the SpatVector -----

# \dontrun{
  if (has_internet()) {
    russia_vector <- gadm(country = "rus", level = 0, path = tempdir())

    russia_vector |> plot_vector()
  }

# }

# Define the SpatRaster -----

# \dontrun{
  if (has_internet()) {
    raster <-
      expand.grid(
        seq(-179.75, 179.75, by = 0.5),
        seq(-89.75, 89.75, by = 0.5)
      ) |>
      as_tibble() |>
      rename(x = Var1, y = Var2) |>
      mutate(value = rnorm(259200)) |>
      rast(type = "xyz") %>%
      `crs<-`("epsg:4326")

    world_shape <- world(path = tempdir())

    raster <- raster |> crop(world_shape, mask = TRUE)
  }
# }

# Visualize the SpatRaster -----

# \dontrun{
  if (has_internet()) {
    raster |> plot_raster()
  }

# }

# Shift, Rotate and Crop the SpatRaster -----

# \dontrun{
  if (has_internet()) {
    raster <- raster |> shift_and_crop(russia_vector, -45)
  }
# }

# Visualize the SpatRaster After Shift and Crop -----

# \dontrun{
  if (has_internet()) {
    raster |> plot_raster()
  }

# }