4、图例标度（legends scale）
图例位置设置
修改ggplot2的图例符号
ggplot2的图例顺序|方向等花里胡哨设置

toy <- data.frame(const = 1, up = 1:4,txt = letters[1:4], big = (1:4)*1000,log = c(2, 5, 10, 2000)
)base <- ggplot(toy, aes(up, up)) + geom_point(aes(colour = txt), size = 3) + xlab(NULL) + ylab(NULL)#legend.position控制图例上下左右位置
p1 <- base + theme(legend.position = "left")
p2 <- base + theme(legend.position = "right") # 默认图例在左边
p3 <- base + theme(legend.position = "bottom")
p4 <- base + theme(legend.position = "none")#不显示图例#legend.position和legend.justification设置图例占比图形比例控制图例位置
base <- ggplot(toy, aes(up, up)) + geom_point(aes(colour = txt), size = 3)
p5 <- base
p6 <- base + theme(legend.position = c(0, 1), legend.justification = c(0, 1))
p7 <- base + theme(legend.position = c(0.5, 0.5), legend.justification = c(0.5, 0.5))
p8 <- base + theme(legend.position = c(1, 0), legend.justification = c(1, 0))
p9 <- grid.arrange(p1,p2,p3,p4,p5,p6,p7,p8,nrow = 4)ggsave("scale8.png", p9, width = 8, height = 10)

options(repr.plot.width = 10, repr.plot.height = 12, repr.plot.res = 300)
p1 <- ggplot(economics_long, aes(date, value01, colour = variable)) +geom_line()#draw_key_timeseries指定图例符号为时间序列
p2 <- ggplot(economics_long, aes(date, value01, colour = variable)) +geom_line(key_glyph = draw_key_timeseries)#自定义图例符号为笑脸
library(grid)
library(rlang)
draw_key_smile <- function(data, params, size) {grobTree(pointsGrob(0.25, 0.75, size = unit(.25, "npc"), pch = 16),pointsGrob(0.75, 0.75, size = unit(.25, "npc"), pch = 16),linesGrob(c(0.9, 0.87, 0.78, 0.65, 0.5, 0.35, 0.22, 0.13, 0.1), c(0.5, 0.35, 0.22, 0.13, 0.1, 0.13, 0.22, 0.35, 0.5)),gp = gpar(col = data$colour %||% "grey20",fill = alpha(data$fill %||% "white", data$alpha),lwd = (data$size %||% 0.5) * .pt,lty = data$linetype %||% 1))
}p3 <- ggplot(economics_long, aes(date, value01, colour = variable)) +geom_line(key_glyph = draw_key_smile)
p4 <- grid.arrange(p1,p2,p3,nrow = 3)ggsave("scale9.png", p4, width = 10, height = 12)

options(repr.plot.width = 5, repr.plot.height = 15, repr.plot.res = 300)
base <- ggplot(mpg, aes(drv, fill = factor(cyl))) + geom_bar() p1 <- base#ncol byrow设置图例排列顺序
p2 <- base + guides(fill = guide_legend(ncol = 2))
p3 <- base + guides(fill = guide_legend(ncol = 2, byrow = TRUE))#reverse颠倒图例顺序
p4 <- base + guides(fill = guide_legend(reverse = TRUE))#override.aes：覆盖从每个图层派生的一些图形属性设置
base1 <- ggplot(mpg, aes(displ, hwy, colour = drv)) +geom_point(size = 4, alpha = .2, stroke = 0)p5 <- base1 + guides(colour = guide_legend())
p6 <- base1 + guides(colour = guide_legend(override.aes = list(alpha = 1)))#axis图例处坐标轴控制
base2 <- ggplot(mpg, aes(displ, manufacturer, size = hwy)) +geom_point(alpha = .2) +scale_size_binned()p7 <- base2
p8 <- base2 + guides(size = guide_bins(axis = FALSE))#direction设置图例方向
p9 <- base2 + guides(size = guide_bins(direction = "vertical"))
p10 <- base2 + guides(size = guide_bins(direction = "horizontal"))#show.limits，axis.colour, axis.linewidth和axis.arrow控制图例处axis属性base3 <- ggplot(mpg, aes(cyl, displ, colour = hwy)) +geom_point(size = 2)#guide_colourbar() / guide_colorbar()控制colourbar型图例
p13 <- base3
p14 <- base3 + guides(colour = guide_colourbar(reverse = TRUE))#设置colourbar高度2cm
p15 <- base3 + guides(colour = guide_colourbar(barheight = unit(2, "cm")))#guide_coloursteps() / guide_colorsteps()控制刻度显示形式
base4 <- ggplot(mpg, aes(displ, hwy, colour = cyl)) + geom_point() + scale_color_binned()p16 <- base4
p17 <- base4 + guides(colour = guide_coloursteps(show.limits = TRUE))#colourbar首尾显示
p18 <- base4 + guides(colour = guide_coloursteps(show.limits = FALSE))p19 <- grid.arrange(p1,p2,p3,p4,p5,p6,p7,p8,p9,p10,p13,p14,p15,p16,p17,p18,nrow = 8)
ggsave("scale10.png", p19, width = 5, height = 15)