Chapter 17 – Creating Faceted Graphics with Lattice

 
# Chapter 17 - Creating Faceted Graphics with Lattice
 
# Creating a Lattice Plot
 
str(mtcars)
 
## Loading the lattice package
 
library("lattice")
 
## Making a lattice scatterplot
 
xyplot(mpg ~ hp | factor(cyl), data=mtcars)
 
## Adding trend lines
 
xyplot(mpg ~ hp | factor(cyl), data=mtcars,
   type=c("p", "r"))
 
 
# Changing Plot Options
 
## Adding titles and labels
 
xyplot(mpg ~ hp | factor(cyl), data=mtcars,
   type=c("p", "r"),
   main="Fuel economy vs. Performance",
   xlab="Performance (horse power)",
   ylab="Fuel economy (miles per gallon)",
)
 
xyplot(mpg ~ hp | factor(cyl), data=mtcars,
   type=c("p", "r"),
   main=list(
       label="Fuel economy vs. Performance given Number of Cylinders",
       cex=0.75)
)
 
## Changing the font size of titles and labels
 
xyplot(mpg ~ hp | factor(cyl), data=mtcars,
   type=c("p", "r"),
   main=list(
       label="Fuel economy vs. Performance given Number of Cylinders",
       cex=0.75),
   xlab=list(
       label="Performance (horse power)",
       cex=0.75),
   ylab=list(
       label="Fuel economy (miles per gallon)",
       cex=0.75),
   scales=list(cex=0.5)
)
 
 
## Using themes to modify plot options
 
xyplot(mpg ~ hp | factor(cyl), data=mtcars,
   type=c("p", "r"),
   par.settings=simpleTheme(col="red", col.line="blue")
)
 
 
# Plotting Different Types
 
## Making a bar chart
 
mtcars$cars <- rownames(mtcars)
 
barchart(cars ~ mpg | factor(cyl), data=mtcars,
   main="barchart",
   scales=list(cex=0.5),
   layout=c(3, 1)
)
 
## Making a box-and-whisker plot
 
bwplot(~ hp | factor(cyl), data=mtcars, main="bwplot")
 
 
# Plotting Data in Groups
 
## Using data in tall format
 
str(longley)
library("reshape2")
mlongley <- melt(longley, id.vars="Year")
 
str(mlongley)
 
xyplot(value ~ Year | variable, data=mlongley,
   layout=c(6, 1),
   par.strip.text=list(cex=0.7),
   scales=list(cex=0.7)
)
 
## Creating a chart with groups
 
mtcars$cars <- rownames(mtcars)
mtcars$am <- with(mtcars, ifelse(am==0, "Automatic", "Manual"))
 
barchart(cars ~ mpg | factor(cyl), data=mtcars,
   group=am,
   scales=list(cex=0.5),
   layout=c(3, 1),
)
 
## Adding a key
 
barchart(cars ~ mpg | factor(cyl), data=mtcars,
   main="barchart with groups",
   group=am,
   auto.key=TRUE,
   par.settings = simpleTheme(col=c("grey80", "grey20")),
   scales=list(cex=0.5),
   layout=c(3, 1)
)
 
 
# Printing and Saving a Lattice Plot
 
## Assigning a lattice plot to an object
 
my.plot <- xyplot(mpg ~ hp | cyl, data=mtcars)
class(my.plot)
 
## Printing a lattice plot in a script
 
xyplot(mpg ~ hp | cyl, data=mtcars)
 
my.plot <- xyplot(mpg ~ hp | cyl, data=mtcars)
print(my.plot)
 
 
## Saving a lattice plot to file
 
setwd("~/")
trellis.device(device="png", filename="xyplot.png")
print(my.plot)
dev.off()

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