ggplot2--Legend(图例操作)

Base Plot

xy <- data.frame(x=1:10, y=10:1, type = rep(LETTERS[1:2], each=5))

p=ggplot(data=xy)+geom_point(aes(x=x,y=y,color=type))

p

legend.background (rect)

# color does not work, use colour instead

p+opts(legend.background=theme_rect(colour="purple",fill="pink",size=3,linetype="dashed"))

legend.key (rect)

p+opts(legend.key=theme_rect(colour='purple',fill='pink',size=0.5,linetype='dashed'))

legend.key.size (unit)

# to use unit, you need to load package grid, i.e. library(grid)

p+opts(legend.key.size=unit(2,'cm'))

legend.key.width (unit)

p+opts(legend.key.width=unit(5,'cm'))

legend.text (text)

p+opts(legend.text = theme_text(colour = 'red', angle = 45, size = 10, hjust = 3, vjust = 3, face = 'bold'))

change legend labels

# breaks=c('A','B'), 'A' and 'B' are the default legend in xy

p+scale_colour_hue(name="my legend", breaks=c('A','B'), labels=c('AAA','BBB'))

legend.title (text)

p+opts(legend.title = theme_text(colour = 'red', angle = 45, size = 10, hjust = 3, vjust = 7, face = 'italic'))

legend.position (?)

# get rid of legend

p+opts(legend.position='none')

# move legend to the left

p+opts(legend.position='left')

#  define relative coordinates on plot c(x, y) between 0 and 1

p+opts(legend.position=c(0.5,0.5))

legend.justification (?)

#  Justification defines which side of the legend that the legend.position coordinates refer to

  p+ opts(legend.justification = 'right', legend.position=c(0.25,0.3))

#  can use left, right, centre or numeric value (0 ≤ x ≤ 1)

Reference

1.  https://github.com/hadley/ggplot2/wiki/Legend-Attributes