sample_lsm function

sample_lsm

Sample metrics

sample_lsm(
  landscape,
  y,
  plot_id = NULL,
  shape = "square",
  size = NULL,
  transform = TRUE,
  all_classes = FALSE,
  return_raster = FALSE,
  verbose = TRUE,
  progress = FALSE,
  ...
)

Arguments

• landscape: A categorical raster object: SpatRaster; Raster* Layer, Stack, Brick; stars or a list of SpatRasters.
• y: 2-column matrix with coordinates or spatial object.
• plot_id: Vector with id of sample points. If not provided, sample points will be labelled 1...n.
• shape: String specifying plot shape. Either "circle" or "square"
• size: Approximated size of sample plot. Equals the radius for circles or half of the side-length for squares in map units. For lines size equals the width of the buffer.
• transform: Logical if planar CRS are transformed to lon/lat for accuracy during area calculations of buffer areas.
• all_classes: Logical if NA should be returned for classes not present in some sample plots.
• return_raster: Logical if the clipped raster of the sample plot should be returned
• verbose: Print warning messages.
• progress: Print progress report.
• ...: Arguments passed on to calculate_lsm().

Returns

tibble

Details

This function samples the selected metrics in a buffer area (sample plot) around sample points, sample lines or within provided polygons. To see more details about arguments passed on to the metrics, please see calculate_lsm().

The metrics can be specified by the arguments what, level, metric, name

and/or type (combinations of different arguments are possible (e.g. level = "class", type = "aggregation metric"). If an argument is not provided, automatically all possibilities are selected. Therefore, to get all

available metrics, don't specify any of the above arguments.

For all metrics based on distances or areas please make sure your data is valid using check_landscape.

Please be aware that the output is slightly different to all other lsm-function of landscapemetrics.

The size of the actual sampled landscape can be different to the provided size due to two reasons. Firstly, because clipping raster cells using a circle or a sample plot not directly at a cell center lead to inaccuracies. Secondly, sample plots can exceed the landscape boundary. Therefore, we report the actual clipped sample plot area relative in relation to the theoretical, maximum sample plot area e.g. a sample plot only half within the landscape will have a percentage_inside = 50. Additionally, if the polygon representing the sample plot is smaller than the cell size of the raster, the percentage_inside may exceed 100%. To calculate the area of the buffer zones, the function terra::expanse() is used. The area results may be influenced by the CRS and the transform argument.

Please be aware that the function behaves differently for POLYGONS and MULTIPOLYGONS. In the first case, each polygon is used as a singular sample area, while in the second case all polygons are used as one sample area.

Examples

landscape <- terra::rast(landscapemetrics::landscape)

# use a matrix
sample_points <- matrix(c(10, 5, 25, 15, 5, 25), ncol = 2, byrow = TRUE)
sample_lsm(landscape, y = sample_points, size = 15, what = "lsm_l_np")

See Also

list_lsm

calculate_lsm