Section 33 ggplot2 legend

33.1 Add Legends to plots

33.1.1 Function

legend

?legend

33.2 Default legends

g <- ggplot(data=iris, 
            mapping=aes(x=Species, y=Sepal.Length, fill=Species))
g <- g + geom_boxplot()
g <- g + labs(title='Boxplot of iris data',
              subtitle = 'Based on iris data',
              x='Species',
              y='Sepal Length (cm)')
g <- g + theme_bw()
g

33.3 Remove legends

# Option 1: Remove legend for a particular aesthetic (fill)
g + guides(fill=FALSE)

# Option 2: Remove all legends
g + theme(legend.position='none')

# Option 3: Remove legend specifying the scale
g + scale_fill_discrete(guide=FALSE)

33.4 Change legend position

g + theme(legend.position='bottom')

g + theme(legend.position='top')

g + theme(legend.position='left')

g + theme(legend.position='right')