The “facet_grid” Function in R

• Package: ggplot2

• Purpose: To create a grid of small multiples in ggplot.

• General Class: Geometric object for facetting into a grid.

• Required Argument(s): None

• Notable Optional Arguments:

• facets: Formula specifying rows and columns.

• scales: Should scales be fixed (“fixed”), free (“free”), or free in one dimension (“free_x” or “free_y”).

• space: If “fixed”, the total space (width or height); if “free”, the space between facets.

• shrink: If TRUE, will shrink scales to fit output of statistics, not raw data.

• labeller: A function that takes one data frame of labels and returns a data frame of labels.

• as.table: If TRUE, the default, the facets are laid out like a table with the highest values at the bottom-right.

• Example:

• # Example usage
  library(ggplot2)
  
  # Create a data frame
  my_data <- data.frame(
  group = rep(c("A", "B", "C"), each = 50),
  values = rnorm(150)
  )
  
  # Create a ggplot object with a facetted grid using facet_grid
  my_plot <- ggplot(data = my_data, aes(x = values, y = after_stat(density))) +
  geom_histogram(binwidth = 0.5, fill = "lightblue", color = "blue", alpha = 0.7) +
  facet_grid(group ~ ., scales = "free_y") +
  labs(title = "Facetted Histogram", x = "Values", y = "Density")
  
  # Print the plot
  print(my_plot)

• In this example, the facet_grid function from the ggplot2 package is used to create a facetted grid of histograms. The function allows the specification of facets using a formula, and optional arguments control the arrangement and scales of the facets.