Program_5

Program-5 Implement an R program to create a histogram illustrating the distribution of a continuous variable, with overlays of density curves for each group, using ggplot2.

###Step 1:Load Required Library We first load ggplot2package,used for data visualization in R.

#install.packages('ggplot2')
library(ggplot2)

###Step 2:Explore the Inbuilt Dataset.

#Use the built-in 'íris' data set.
#'Petal.Length' is a continuous variable.
#'Species' is a categorical grouping variable

str(iris)

'data.frame':   150 obs. of  5 variables:
 $ Sepal.Length: num  5.1 4.9 4.7 4.6 5 5.4 4.6 5 4.4 4.9 ...
 $ Sepal.Width : num  3.5 3 3.2 3.1 3.6 3.9 3.4 3.4 2.9 3.1 ...
 $ Petal.Length: num  1.4 1.4 1.3 1.5 1.4 1.7 1.4 1.5 1.4 1.5 ...
 $ Petal.Width : num  0.2 0.2 0.2 0.2 0.2 0.4 0.3 0.2 0.2 0.1 ...
 $ Species     : Factor w/ 3 levels "setosa","versicolor",..: 1 1 1 1 1 1 1 1 1 1 ...

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

head(iris,n=2)

  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

tail(iris)

    Sepal.Length Sepal.Width Petal.Length Petal.Width   Species
145          6.7         3.3          5.7         2.5 virginica
146          6.7         3.0          5.2         2.3 virginica
147          6.3         2.5          5.0         1.9 virginica
148          6.5         3.0          5.2         2.0 virginica
149          6.2         3.4          5.4         2.3 virginica
150          5.9         3.0          5.1         1.8 virginica

tail(iris,n=2)

    Sepal.Length Sepal.Width Petal.Length Petal.Width   Species
149          6.2         3.4          5.4         2.3 virginica
150          5.9         3.0          5.1         1.8 virginica

###Step 3:Initializing the plot.

We start by creating a basic ggplot object and mapping the variables.

#Start ggplot with iris dataset
#map Petal.Length to x-axis and fill by Species.

p <- ggplot(data = iris, aes(x = Petal.Length,fill=Species))
p

#Add histogram with density scaling

p <- p + geom_histogram(aes(y= ..density..),
alpha=0.4,
position = "identity",
bins=30 )
p

Warning: The dot-dot notation (`..density..`) was deprecated in ggplot2 3.4.0.
ℹ Please use `after_stat(density)` instead.

#Overlay density curves for each group

p <- p+
geom_density(aes(color=Species),
size=1.2)

Warning: Using `size` aesthetic for lines was deprecated in ggplot2 3.4.0.
ℹ Please use `linewidth` instead.

p

#Add title and axis labels, and apply clean theme.

p<- p+ labs(
  title = "Distribution of petal Length with Group-wise Density Curves",
  x= "Petal Length",
  y= "Density")+
  theme_minimal()

p

#Add title and axis labels, and apply clean theme.

p<- p+ labs(
  title = "Distribution of petal Length with Group-wise Density Curves",
  x= "Petal Length",
  y= "Density")+
  theme_minimal()+
  theme(legend.position='top')
  p