divid_plot: Divide 1 ha square plots into 25 squares subplots of 400m²...

In gdauby/bdd_plots_central_africa: Exploring and updating the Central Africa plot database

Divide 1 ha square plots into 25 squares subplots of 400m² following a regular 5*5 grid

Description

Divide 1 ha square plots into 25 squares subplots of 400m² following a regular 5*5 grid

Usage

divid_plot(coordinates_sf, plot_name = "plot_name")

Arguments

coordinates_sf	a spatial object representing the plot geometries, either a SpatialPolygonsDataFrame or sf object. Each line should correspond to a single plot.
plot_name	the name as character of the column where the plot name are stored. Default value is 'plot_name'.

Details

The function takes either a SpatialPolygonsDataFrame or sf object containing the plot geometries and the plot names. For each plot, it first identifies the 4 corners, then creates the 25 square subplots following a regular 5*5 grid. The subplots are named using the xy coordinates inside the plot, starting from 0_0 for the southeasterly corner to 80_80 for the northwesternly.

Value

A sf object with the 25 subplots geometries with 2 fields : sous_plot_name and plot_name for each plot.

Author(s)

Hugo Leblanc

Examples

## Test 1

# Define the coordinates of the 4 corners
x1 <- c(0, 1, 1, 0, 0)
y1 <- c(0, 0, 1, 1, 0)
x2 <- c(2, 2, 3, 3, 2)
y2 <- c(1, 2, 2, 1, 1)

# Combine x and y coordinates into matrix
coords1 <- cbind(x1, y1)
coords2 <- cbind(x2, y2)

# Rotate by 20 degrees the matrix coord1
angle <- pi/9  # angle in radians
rotation_mat <- matrix(c(cos(angle), sin(angle), -sin(angle), cos(angle)), nrow = 2)
coords1 <- coords1 %*% rotation_mat

# Create SF object
poly1 <- st_sfc(st_polygon(list(coords1)))
poly2 <- st_sfc(st_polygon(list(coords2)))

coordinates_sf <-
  st_as_sf(data.frame(
    plot_name = c('Plot_001', 'Plot_002'),
    geometry = c(poly1, poly2)
  ))

#Plot
plot(coordinates_sf$geometry)

# Divide the plot into smaller squares
sub_plot <- divid_plot(coordinates_sf = coordinates_sf, plot_name = 'plot_name')

# Plot the plots and the result subplots
par(mfrow = c(1, 2))
plot(coordinates_sf$geometry, main = "Plots")
plot(sub_plot$geometry, main = "Subplots")

# Plot the plots and the result subplots
library(ggplot2)
ggplot(sub_plot)  +
  geom_sf() +
  scale_fill_continuous(type = 'viridis')+
  geom_sf_text(aes(label = as.character(sous_plot_name)))

## Test 2
library(plotsdatabase)

# Extract datas
x <- query_plots(locality_name = "Mbalmayo", extract_individuals = TRUE, show_all_coordinates = TRUE)

coordinates_sf <- x$coordinates_sf
sub_plot <- divid_plot(coordinates_sf,'plot_name')

par(mfrow = c(1, 1))
for(i in 1:length(unique(sub_plot$plot_name))) {

  print(ggplot(sub_plot %>% filter(plot_name == unique(plot_name)[i]))  +
          geom_sf() +
          scale_fill_continuous(type = 'viridis')+
          geom_sf_label(aes(label = as.character(sous_plot_name)))  +
          ggtitle(paste(unique(unique(sub_plot$plot_name)[i]))) )
}

gdauby/bdd_plots_central_africa documentation built on April 12, 2024, 1:15 a.m.