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Generate Spatial Grid and Gridded Summaries

Source: R/generate_grid.R
generate_grid.Rd

Builds a regular lattice over a point-occurrence data set, assigns every record a grid_id, and returns grid-level summaries in both abundance and presence/absence formats.

Usage

generate_grid(
  data,
  x_col = "x",
  y_col = "y",
  grid_size = 0.5,
  sum_cols = NULL,
  extra_cols = NULL,
  crs_epsg = 4326,
  unit = c("deg", "min", "sec", "m")
)

Arguments

data

Data frame of points with x–y coordinates.

x_col,

y_col Column names for longitude and latitude.

grid_size

Cell size (degrees or metres, depending on CRS).

sum_cols

Character or numeric vector of columns to aggregate. Note: Numeric indices are converted to names internally.

extra_cols

Additional columns to keep (optional).

crs_epsg

EPSG code of the coordinate reference system.

unit

One of "deg", "min", "sec", or "m".

Value

A list containing • grid_r – multi-layer SpatRaster • grid_sf – polygon lattice with centroids & metrics • grid_spp – abundance summary (data.frame) • grid_spp_pa – presence/absence summary (data.frame)

Details

The function:

  1. Tiles the study extent with square cells of size grid_size.

  2. Computes cell centroids and, for geographic CRS data, optional mapsheet codes (1:250 000 “BB” series).

  3. Aggregates user-specified columns (sum_cols) per cell, producing

    • grid_spp – counts / abundances

    • grid_spp_pa – binary 0 / 1 table for dissimilarity analyses.

  4. Calculates helper metrics (obs_sum, spp_rich) for each cell.

  5. Rasterises key layers (grid_id, obs_sum, spp_rich) and preserves any extra metadata supplied via extra_cols.

Examples

set.seed(123)
data = data.frame(
  x = runif(100, -10, 10),
  y = runif(100, -10, 10),
  species1 = rpois(100, 5),
  species2 = rpois(100, 3),
  recordedBy = sample(LETTERS, 100, replace = TRUE)
)
grid_result = generate_grid(data, x_col = "x", y_col = "y",
                             grid_size = 1, sum_cols = 3:4,
                             extra_cols = c("recordedBy"))
#> Generating 1-deg grid …
print(grid_result$block_sp)
#> NULL
plot(grid_result$grid_sf["grid_id"])