本文詳細介紹ggplot2中圖例標度（legends scales），續前篇

• R可視化07|ggplot2圖層-標度圖層（scale layer）-顏色盤篇

本文目錄

4、圖例標度（legends scale） 圖例位置設置 修改ggplot2的圖例符號 ggplot2的圖例順序|方向等花里胡哨設置

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4、圖例標度（legends scale）

• 圖例位置設置

圖例位置通過theme中的legend.position設置，有參數“right”, “left”, “top”, “bottom”, or “none” (不顯示圖例)可選。

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控制圖例上下左右位置 p1 <- base + theme(legend.position = "left") p2 <- base + theme(legend.position = "right") # 默認圖例在左邊 p3 <- base + theme(legend.position = "bottom") p4 <- base + theme(legend.position = "none")#不顯示圖例#legend.position和legend.justification設置圖例占比圖形比例控制圖例位置 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)

• 修改ggplot2的圖例符號draw_key_*函數指定圖例符號，注意右側圖例符號變化。

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指定圖例符號為時間序列 p2 <- ggplot(economics_long, aes(date, value01, colour = variable)) +geom_line(key_glyph = draw_key_timeseries)#自定義圖例符號為笑臉 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)

其它draw_key_*圖例符號

• ggplot2的圖例順序|方向等花里胡哨設置

這部分詳細介紹圖例各種個性化設置，看圖找代碼即可。

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設置圖例排列順序 p2 <- base + guides(fill = guide_legend(ncol = 2)) p3 <- base + guides(fill = guide_legend(ncol = 2, byrow = TRUE))#reverse顛倒圖例順序 p4 <- base + guides(fill = guide_legend(reverse = TRUE))#override.aes：覆蓋從每個圖層派生的一些圖形屬性設置 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圖例處坐標軸控制 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設置圖例方向 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控制圖例處axis屬性base3 <- ggplot(mpg, aes(cyl, displ, colour = hwy)) +geom_point(size = 2)#guide_colourbar() / guide_colorbar()控制colourbar型圖例 p13 <- base3 p14 <- base3 + guides(colour = guide_colourbar(reverse = TRUE))#設置colourbar高度2cm p15 <- base3 + guides(colour = guide_colourbar(barheight = unit(2, "cm")))#guide_coloursteps() / guide_colorsteps()控制刻度顯示形式 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首尾顯示 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)

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