divide_plot: Divides one ore more plots into subplots

In BIOMASS: Estimating Aboveground Biomass and Its Uncertainty in Tropical Forests

Divides one ore more plots into subplots

Description

This function divides a plot (or several plots) into subplots in the relative coordinates system, and returns the coordinates of subplot corners.

Usage

divide_plot(
  corner_data,
  rel_coord,
  proj_coord = NULL,
  grid_size,
  tree_data = NULL,
  tree_coords = NULL,
  corner_plot_ID = NULL,
  tree_plot_ID = NULL,
  grid_tol = 0.1,
  centred_grid = F
)

Arguments

corner_data	A data frame, data frame extension, containing the plot corner coordinates. Typically, the output ⁠$corner_coord⁠ of the check_plot_coord() function.
rel_coord	A character vector of length 2, specifying the column names (resp. x, y) of the corner relative coordinates.
proj_coord	A character vector of length 2, specifying the column names (resp. x, y) of the corner projected coordinates.
grid_size	A vector indicating the dimensions of grid cells (resp. X and Y dimensions). If only one value is given, grid cells will be considered as squares.
tree_data	A data frame containing tree relative coordinates and other optional tree metrics (one row per tree).
tree_coords	A character vector of length 2, specifying the column names of the relative coordinates of the trees.
corner_plot_ID	If dealing with multiple plots : a vector indicating plot IDs for corners.
tree_plot_ID	If dealing with multiple plots : a vector indicating tree plot IDs.
grid_tol	A numeric between (0;1) corresponding to the percentage of the plot area allowed to be excluded from the plot division (when grid_size doesn't match exactly plot dimensions).
centred_grid	When grid_size doesn't match exactly plot dimensions, a logical indicating if the subplot grid should be centered on the plot.

Details

If corner coordinates in the projected coordinate system are supplied (proj_coord), projected coordinates of subplot corners are calculated by a bilinear interpolation in relation with relative coordinates of plot corners. Be aware that this bilinear interpolation only works if the plot in the relative coordinates system is rectangular (ie, has 4 right angles).

Value

If tree_data isn't supplied, returns a data-frame containing as many rows as there are corners corresponding to the subplots, and the following columns :

• corner_plot_ID: If dealing with multiple plots : the plot code

• subplot_ID: The automatically generated subplot code, using the following rule : subplot_X_Y

• x_rel and y_rel : the relative X-axis and Y-axis coordinates of subplots corners.

• x_proj and y_proj : if proj_coord is supplied, the projected X-axis and Y-axis coordinates of subplots corners

If tree_data is supplied, returns a list containing :

• the previous data-frame

• the tree_data data-frame with the subplot_ID of each tree in the last column

Author(s)

Arthur PERE, Arthur BAILLY

Examples

# One plot with repeated measurements of each corner
data("NouraguesPlot201")
check_plot201 <- check_plot_coord(
  corner_data = NouraguesPlot201,
  proj_coord = c("Xutm","Yutm"), rel_coord = c("Xfield","Yfield"),
  trust_GPS_corners = TRUE, draw_plot = FALSE)
subplots_201 <- divide_plot(
  corner_data = check_plot201$corner_coord, 
  rel_coord = c("x_rel","y_rel"), proj_coord = c("x_proj","y_proj"),
  grid_size = 50)
subplots_201

# Assigning trees to subplots
data("NouraguesTrees")
plot201_trees <- NouraguesTrees[NouraguesTrees$Plot == 201,]
subplots_201 <- suppressWarnings(
  divide_plot(
    corner_data = check_plot201$corner_coord, 
    rel_coord = c("x_rel","y_rel"), proj_coord = c("x_proj","y_proj"),
    grid_size = 50,
    tree_data = plot201_trees, tree_coords = c("Xfield","Yfield")))
head(subplots_201$sub_corner_coord)
head(subplots_201$tree_data)

# When grid dimensions don't fit perfectly plot dimensions

  divide_plot(
    corner_data = check_plot201$corner_coord, 
    rel_coord = c("x_rel","y_rel"),
    grid_size = c(41,41),
    grid_tol = 0.4, centred_grid = TRUE)


# Dealing with multiple plots
data("NouraguesCoords")
nouragues_subplots <- suppressWarnings(
  divide_plot(
    corner_data = NouraguesCoords,
    rel_coord = c("Xfield","Yfield"), proj_coord = c("Xutm","Yutm"),
    corner_plot_ID = "Plot",
    grid_size = 50,
    tree_data = NouraguesTrees, tree_coords =  c("Xfield","Yfield"),
    tree_plot_ID = "Plot"))
head(nouragues_subplots$sub_corner_coord)
head(nouragues_subplots$tree_data)

BIOMASS documentation built on April 3, 2025, 6:09 p.m.