Extract or Access Parts of an ea_spatial Object

Provides access to metadata and data using the [[ operator. This allows for intuitive extraction of metadata fields, the full data object, or specific columns/layers within the data object.

Subsets the data slot of an ea_spatial object using the [ operator, while preserving the object's structure and metadata.

Usage

# S4 method for class 'ea_spatial'
x[[i, j, ...]]

# S4 method for class 'ea_spatial,ANY,ANY,ANY'
x[i, j, ..., drop = FALSE]

Arguments

x

An ea_spatial object.

i

Row/feature indices (numeric, logical), or a spatial object (sf, sfc) to use for spatial subsetting.

j

Ignored. A warning is issued if j is specified for sf/stars.

...

Additional arguments passed to the underlying subset method.

drop

Logical. Passed to the underlying subset method.

Value

The requested element. For SpatRaster layers, this returns the raster values as a vector via terra::values().

A new ea_spatial object with a subsetted data slot.

Details

This method is primarily intended for spatial or feature-based subsetting (i.e., by row index or by another spatial object). Column subsetting (via j) is not supported for sf or stars objects to prevent accidental removal of the required value or geometry columns.

Examples

if (requireNamespace("sf", quietly = TRUE)) {
  # Create a sample sf object
  pts <- list(sf::st_point(c(-63, 44)), sf::st_point(c(-66, 45)))
  sf_df <- sf::st_sf(temp = c(12, 13), geometry = sf::st_sfc(pts, crs = 4326))
  obj <- ea_spatial(sf_df, "temp", "temp", "region", "time", "C")

  # Get a metadata field
  obj[["units"]]

  # Get the 'value' vector from the data
  obj[["value"]]
}
#> [1] 12 13
if (requireNamespace("sf", quietly = TRUE)) {
  pts <- list(sf::st_point(c(-63, 44)), sf::st_point(c(-66, 45)))
  sf_df <- sf::st_sf(temp = c(12, 13), geometry = sf::st_sfc(pts, crs = 4326))
  obj <- ea_spatial(sf_df, "temp", "temp", "region", "time", "C")

  # Subset the first feature
  obj[1, ]
}
#> An object of class "ea_spatial"
#> Slot "meta":
#> $data_type
#> [1] "temp"
#> 
#> $region
#> [1] "region"
#> 
#> $time_descriptor
#> [1] "time"
#> 
#> $units
#> [1] "C"
#> 
#> $source_citation
#> [1] "No citation provided"
#> 
#> $original_value_col
#> [1] "temp"
#> 
#> 
#> Slot "data":
#> Simple feature collection with 1 feature and 1 field
#> Geometry type: POINT
#> Dimension:     XY
#> Bounding box:  xmin: -63 ymin: 44 xmax: -63 ymax: 44
#> Geodetic CRS:  WGS 84
#>   value       geometry
#> 1    12 POINT (-63 44)
#>