generate_variogram_plot: Generate Variogram Plot

Description

Creates a variogram plot showing the spatial dependence structure of the data. The plot includes both the empirical variogram points and the fitted theoretical variogram line. The empirical variogram points show the actual semivariance values at different distances, while the red line shows the fitted exponential variogram model.

Usage

generate_variogram_plot(
  age_param_data,
  fit_vario,
  country_code,
  scale_outcome = "log_scale",
  output_dir,
  width = 12,
  height = 9,
  png_resolution = 300
)

Value

Invisibly returns the ggplot object containing the variogram plot. The plot is also saved as a PNG file in the specified output directory.

Arguments

age_param_data: Data frame containing the age parameter data. Must include columns 'web_x' and 'web_y' for spatial coordinates and the response variable specified in scale_outcome.
fit_vario: Fitted variogram object from automap package. Should contain components $psill (partial sill) and $range (range parameter) for the exponential variogram model.
country_code: Character string of the country code (e.g. "TZA") used for plot title and output filename.
scale_outcome: Character string specifying the column name for the scale parameter response variable (default: "log_scale"). This is the variable for which the variogram is computed.
output_dir: Character string specifying the directory path where the plot will be saved as a PNG file.
width: Plot width in pixels (default: 2000). Controls the output image width.
height: Plot height in pixels (default: 1500). Controls the output image height.
png_resolution: PNG resolution in DPI (dots per inch, default: 300). Higher values create larger, higher quality images.

Details

The function creates a variogram plot with the following elements: - Points showing empirical semivariance values at different distances - A red line showing the fitted exponential variogram model - Clear axis labels and title - Comma-formatted distance values on x-axis - Clean theme with black and white style

The output filename is constructed as lowercase country code + "_variogram.png"

Examples

Run this code

# \donttest{
set.seed(123)  # For reproducibility
age_param_data <- data.frame(
  country = rep("TZA", 100),
  web_x = runif(100, 0, 100),
  web_y = runif(100, 0, 100),
  log_scale = rnorm(100, mean = 5, sd = 2)
)

# Create a dummy fitted variogram object
fit_vario <- list(
  psill = c(0.1, 0.5),
  range = c(0, 50)
)

vario_plot <- generate_variogram_plot(
   age_param_data = age_param_data,
   fit_vario = fit_vario,
   country_code = "TZA",
   output_dir = file.path(tempdir()))
# }