Program_10

##Program: Develop an R function to draw a density curve representing the probability density function of a continuous variable, with separate curves for each group, using ggplot2.

##Objective: to draw a density curve representing the probability density of a continuous variable, with separate curves for each group, using ggplot2.

###Step 1: Load Required Library -ggplot2 to create density plots.

#Load the ggplot2 package
library(ggplot2)

###Step 2: we will create a function called plot_density_by_group()

plot_density_by_group <- function(data, continuous_var, group_var,
                                  fill_colors = NULL) {
  
  # Check if the specified columns exist
  if (!(continuous_var %in% names(data)) || !(group_var %in% names(data))) {
    stop("Invalid column names. Make sure both variables exist in the dataset.")
  }
  
  # Create the ggplot object
  p <- ggplot(data, aes_string(x = continuous_var, 
                               color = group_var, 
                               fill = group_var)) +
    geom_density(alpha = 0.4) +
    labs(
      title = paste("Density Plot of", continuous_var, "by", group_var),
      x = continuous_var,
      y = "Density"
    ) +
    theme_minimal()
  
  # Apply custom colors if provided
  if (!is.null(fill_colors)) {
    p <- p + scale_fill_manual(values = fill_colors) +
             scale_color_manual(values = fill_colors)
  }
#Return the plot  
  return(p)
}

#Basic usage
plot_density_by_group(iris, "Sepal.Length", "Species")

Warning: `aes_string()` was deprecated in ggplot2 3.0.0.
ℹ Please use tidy evaluation idioms with `aes()`.
ℹ See also `vignette("ggplot2-in-packages")` for more information.

#Define custom, colors
custom_colors <- c("setosa"= "steelblue",
                   "versicolor"= "forestgreen",
                   "virginica"= "darkorange")
                  
#Plot with custom colors
plot_density_by_group(iris, "Petal.Length", "Species", fill_colors=custom_colors)

plot_density_by_group(iris, "Sepal.Width", "Species", fill_colors=custom_colors)

plot_density_by_group(iris, "Sepal.Length", "Species", fill_colors=custom_colors)

plot_density_by_group(iris, "Petal.Width", "Species", fill_colors=custom_colors)