R Graphics

options.orig <- options(repr.plot.width=4, repr.plot.height=4)

Base Graphics

This is the graphics you get ont of the box, without loading any packages. It is not the prettiest, but great for quick plotting.

Scatter plot

plot(1:10, 1:10)

Rotate labels

plot(1:10, 1:10, las=1)

Marker symbols

plot(1:10, 1:10, pch=1:10)

Marker size

plot(1:10, 1:10, pch=1:10, cex=1:10)

Marker colors

plot(1:10, 1:10, pch=1:10, cex=1:10, col=1:10)

Adding text labels

plot(1:10, 1:10, pch=1:10, col=1:10, xlim=c(0, 11))
text(1:10+1, 1:10, 1:10)

Line plot

n <- 20
x <- 1:n
y <- x + rnorm(n)

plot(x, y, type="l", lty=1, lwd=2, col="red",
     main="Plot", xlab="Foo", ylab="Bar")
points(x, y, col="blue")

m <- lm(y ~ x)
plot(x, y, col="blue")
abline(m, col="red", lty="dashed")

Histogram

hist(y)

Barplot

barplot(y)

g <- sample(1:3, n, replace=T)
z <- rnorm(n)

boxplot(z ~ g)

QQ plots

x <- rnorm(100)

qqnorm(x)
qqline(x)

y <- rgamma(100, shape=1)

qqnorm(y)
qqline(y)

Multiple plots

We can set up multiple plots with

par(mfrow=c(#rows, #cols))

where plots will be placed by row first

or

par(mfcol=c(#rows, #cols))

where plots will be placed by colum first.

options.orig <- options(repr.plot.width=6, repr.plot.height=6)

par(mfrow=c(2,2))
plot(x, y)
plot(x, y, type="l")
barplot(x)
barplot(y)
par(mfrow=c(1,1))

Saving plots

Saving a plot involves

• opening a graphcis file device using png (or pdf)

• issuing plot commands

• then closing the device with dev.off().

png('figs/lm.png')
m <- lm(y ~ x)
plot(x, y, col="blue")
abline(m, col="red", lty="dashed")
dev.off()

png: 2

Retreive the PNG file