STAT GU4206/GR5206 Practice Lab Base R Graphics

Description

Background: Edgar Anderson’s Iris Data
The R data description follows:
This famous (Fisher’s or Anderson’s) iris data set gives the measurements in centimeters of the variables
sepal length and width and petal length and width, respectively, for 50 flowers from each of 3 species of iris.
The species are Iris setosa, versicolor, and virginica.
Tasks
The purpose of this lab is to construct two complex plots using base R graphics.
1) Construct the exact plot Gabrielplot.png that is posted on Canvas. Move the legend to the topleft,
change the xlab & ylab to Sepal Length & Petal Length respectively, and change the title to
something else.
## R code goes here
2) Plot four normal distributions using different colors and placing line segments at the mean of each
distribution. Include a legend, update the title and change the vertical & horizontal limits so that the
plot looks nice. Use the function dnorm() to plot the normal density. The normal distributions are:
N(µ = 0, σ2 = 1), N(µ = 2, σ2 = 9/16), N(µ = −2, σ2 = 4), N(µ = 4, σ2 = 1/4),
Note that the function dnorm() uses standard deviation (σ) and do not use variance (σ
2
). The code below
should get you started.
# Define x and y points
x <- seq(-10,10,by=.01)
normal_1 <- dnorm(x,mean=0,sd=1)
# Construct base plot
# Plot x and y points and connect the dots
plot(x,normal_1,
xlim=c(-5,5),ylim=c(-.2,.6),
type=”l”,col=”blue”,
ylab=”Densities”,
main=”Normal Distributions”)
1
# Use lines() to add other plots
# Line segements
segments(x0=0,y0=0,x1=0,y1=dnorm(0,mean=0,sd=1),lty=3)
# Legend
legend(“topleft”,legend=c(“N(0,1)”),
col=c(“blue”),
lty=c(1,1,1,1),cex=1)
# Horizontal axis
abline(h=0,lty=2)
−4 −2 0 2 4
−0.2 0.0 0.2 0.4 0.6
Normal Distributions
x
Densities
N(0,1)