Create a plot sample.

Creates a plot sample on a regular grid with a random start location.

Usage

plotsample(spdf, boundary, x.ppn = 0.25, y.ppn = 0.25, nx = 5, ny = 5)

Arguments

spdf

A SpatialPointsDataFrame defining the points that are to be sampled by the plot sample.

boundary

A SpatialPolygonsDataFrame defining the survey boundary within which the points occur.

x.ppn

The proportion of the x=axis that is to be included in the plots.

y.ppn

The proportion of the y=axis that is to be included in the plots.

nx

The number of plots in the x-dimension.

ny

The number of plots in the y-dimension.

Value

A list with three components:

plots

A SpatialPolygonsDataFrame object containing the plots that were sampled.

dets

A SpatialPointsDataFrame object containing the locations of the points within the plots.

counts

A dataframe containing the following columns

x

The x-coordinates of the centres of the plots within the boundary.

y

The y-coordinates of the centres of the plots within the boundary.

n

The numbers of points in each plot.

area

The areas of the plots within the boundary

.

Examples

# \donttest{
# Some features require the raster package
if (bru_safe_sp() &&
  require("sp") &&
  require("raster", quietly = TRUE) &&
  require("ggplot2", quietly = TRUE) &&
  require("terra", quietly = TRUE) &&
  require("sf", quietly = TRUE)) {
  gorillas <- gorillas_sp()
  plotpts <- plotsample(gorillas$nests, gorillas$boundary,
    x.ppn = 0.4, y.ppn = 0.4, nx = 5, ny = 5
  )
  ggplot() +
    gg(plotpts$plots) +
    gg(plotpts$dets, pch = "+", cex = 2) +
    gg(gorillas$boundary)
}
#> 
#> Attaching package: ‘raster’
#> The following object is masked from ‘package:tidyterra’:
#> 
#>     select
#> The following object is masked from ‘package:dplyr’:
#> 
#>     select

# }