program 10

Develop an r function to draw a density curve representing the probablitlity density function of a continuous varaiable,with seperate curves for each group,using ggplot2.

step1:load the necessary libraray

library(ggplot2)

step2:define the function

plot_density_by_group <- function(data, continuous_var , group_var , fill_colors = NULL){
   if(!(continuous_var %in% names(data)) || !(group_var %in% names(data))){
     stop("invalid column names.make sure both varaiables exist in the dataset.")
   }
  p <- ggplot(data,aes_string(x = continuous_var , color = group_var , fill = group_var))+
    geom_density(aplha = 0.4)+
    labs(title = paste("density plot of",continuous_var,"by",group_var),
         x = "continous_var",
         y = "density")+
    theme_minimal()
  if (!is.null(fill_colors))
  {
    p <-p+scale_fill_manual(values = fill_colors)+
      scale_color_manual(values = fill_colors)
  }
  return(p)
}

step3::Load dataset

data(iris)
head(iris)

  Sepal.Length Sepal.Width Petal.Length Petal.Width Species
1          5.1         3.5          1.4         0.2  setosa
2          4.9         3.0          1.4         0.2  setosa
3          4.7         3.2          1.3         0.2  setosa
4          4.6         3.1          1.5         0.2  setosa
5          5.0         3.6          1.4         0.2  setosa
6          5.4         3.9          1.7         0.4  setosa

step 4: call the function with example

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.

Warning in geom_density(aplha = 0.4): Ignoring unknown parameters: `aplha`