FINAL TERM EXERCISE 3

CHAPTER 5 SCATTERPLOTS

Creating a Basic Scatter Plot

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

with(iris, plot(Petal.Length ~ Petal.Width))

## Optional Parameters

par(mfrow=c(1,1),mar=c(5,4,2,4))
with(iris,plot(Petal.Length ~ Petal.Width, 
     col= "purple",
     pch= 5, 
     main= "Petal Lengths and Widths", 
     ylab= "Petal length (cm)", 
     xlab= "Petal width (cm)", 
     ylim= c(0,8), 
     xlim= c(0,3), 
     las= 1 ))

Scatter Plots with a Grouping Variable

par(mfrow=c(1,1),mar=c(5,4,2,4))
with(iris,plot(Petal.Length ~ Petal.Width, 
     col= Species,
     pch= 16, 
     main= "Petal Lengths and Widths by Species", 
     ylab= "Petal length (cm)",        
     xlab= "Petal width (cm)",                 
     ylim= c(0,8),                    
     xlim= c(0,3),                   
     las= 1))  
summary(iris$Species)

##     setosa versicolor  virginica 
##         50         50         50

legend("bottomright",
       title= "Species", 
       legend= c("Setosa", "versicolor", "virginica"),
       col= 1:3,
       pch= 16, 
       bty= "n")

## Advanced Scatter Plot Features

par(mar=c(5,4,0,4))
with(iris,plot(Petal.Length ~ Petal.Width,
               col= c("darkorchid1","darkorchid","darkorchid4")[as.numeric(Species)],
     pch= 19)) 
legend("topleft", 
       title="Species", 
       legend= c("setosa", "versicolor","virginica"),
       col= c("darkorchid1", "darkorchid", "darkorchid4"),
       pch= 19,
       bty="n")

par(mar=c(5,4,2,4))
with(iris,plot(Petal.Length ~Petal.Width,
               col= c("grey10","grey50", "grey80") [as.numeric(Species)],
               pch= c(6,19,21)[as.numeric(Species)],
     main= "Petal Lengths and Widths",
     ylab= "Petal length (cm)",
     xlab= "Petal width (cm)",
     ylim= c(0,8),
     xlim= c(0,3),
     las= 1))
legend("bottomright",               
       title= "Species",           
       legend= c("setosa","versicolor","virginica"),
       col= c("grey10", "grey50", "grey80"),
       pch= c(6,19,21),
       bty="n")