在图形上显示文本，或者标签（与文本的区别是在文本外有一个矩阵边框）是常规需求。用 ggplot2 画图时，有一个默认的几何对象 geom_text 在图上添加文本，但有时候表现得并不好，比如文本与点重叠在一起，文本与文本之间重叠在一起。
ggrepel 包就是专为解决这一问题而开发的，它有两个几何对象，分别用来解决文本或标签的重叠问题：
- geom_text_repel()
- geom_label_repel()
先看一看默认的 geom_text 与 geom_text_repel 的对比：
代码语言：javascript复制library(ggrepel)
library(patchwork)
set.seed(42)
dat <- subset(mtcars, wt > 2.75 & wt < 3.45)
dat$car <- rownames(dat)
p <- ggplot(dat, aes(wt, mpg, label = car))
geom_point(color = "red")
p1 <- p geom_text() labs(title = "geom_text()")
p2 <- p geom_text_repel() labs(title = "geom_text_repel()")
p1 p2
示例
隐藏部分标签
代码语言：javascript复制set.seed(42)
dat2 <- subset(mtcars, wt > 3 & wt < 4)
# Hide all of the text labels.
dat2$car <- ""
# Let's just label these items.
ix_label <- c(2, 3, 14)
dat2$car[ix_label] <- rownames(dat2)[ix_label]
ggplot(dat2, aes(wt, mpg, label = car))
geom_text_repel()
geom_point(color = ifelse(dat2$car == "", "grey50", "red"))
显示标签，即使它们之间有大量重叠
代码语言：javascript复制set.seed(42)
n <- 15
dat4 <- data.frame(
x = rep(1, length.out = n),
y = rep(1, length.out = n),
label = letters[1:n]
)
# Set it globally:
options(ggrepel.max.overlaps = Inf)
p1 <- ggplot(dat4, aes(x, y, label = label))
geom_point()
geom_label_repel(box.padding = 0.5, max.overlaps = 10)
labs(title = "max.overlaps = 10 (default)")
p2 <- ggplot(dat4, aes(x, y, label = label))
geom_point()
geom_label_repel(box.padding = 0.5)
labs(title = "max.overlaps = Inf")
p1 p2
## Warning: ggrepel: 15 unlabeled data points (too many overlaps). Consider
## increasing max.overlaps
总是（或从不）画线段
代码语言：javascript复制p <- ggplot(dat, aes(wt, mpg, label = car))
geom_point(color = "red")
p1 <- p
geom_text_repel(min.segment.length = 0, seed = 42, box.padding = 0.5)
labs(title = "min.segment.length = 0")
p2 <- p
geom_text_repel(min.segment.length = Inf, seed = 42, box.padding = 0.5)
labs(title = "min.segment.length = Inf")
p1 p2
限制标签在一个特殊区域
代码语言：javascript复制set.seed(42)
# All labels should be to the right of 3.
x_limits <- c(3, NA)
p <- ggplot(dat)
aes(
x = wt, y = mpg, label = car,
fill = factor(cyl), segment.color = factor(cyl)
)
geom_vline(xintercept = x_limits, linetype = 3)
geom_point()
geom_label_repel(
color = "white",
arrow = arrow(
length = unit(0.03, "npc"), type = "closed", ends = "first"
),
xlim = x_limits,
point.padding = NA,
box.padding = 0.1
)
scale_fill_discrete(
name = "cyl",
# The same color scall will apply to both of these aesthetics.
aesthetics = c("fill", "segment.color")
)
p
## Warning: Removed 1 rows containing missing values (`geom_vline()`).
排列标签在上下边缘
代码语言：javascript复制set.seed(42)
ggplot(mtcars, aes(x = wt, y = 1, label = rownames(mtcars)))
geom_point(color = "red")
geom_text_repel(
force_pull = 0, # do not pull toward data points
nudge_y = 0.05,
direction = "x",
angle = 90,
hjust = 0,
segment.size = 0.2,
max.iter = 1e4, max.time = 1
)
xlim(1, 6)
ylim(1, 0.8)
theme(
axis.line.y = element_blank(),
axis.ticks.y = element_blank(),
axis.text.y = element_blank(),
axis.title.y = element_blank()
)
set.seed(42)
dat <- mtcars
dat$car <- rownames(dat)
ggplot(dat, aes(qsec, mpg, label = car))
geom_text_repel(
data = subset(dat, mpg > 30),
nudge_y = 36 - subset(dat, mpg > 30)$mpg,
segment.size = 0.2,
segment.color = "grey50",
direction = "x"
)
geom_point(color = ifelse(dat$mpg > 30, "red", "black"))
scale_x_continuous(expand = c(0.05, 0.05))
scale_y_continuous(limits = c(NA, 36))
排列标签在左右边缘
代码语言：javascript复制set.seed(42)
p <- ggplot(mtcars, aes(y = wt, x = 1, label = rownames(mtcars)))
geom_point(color = "red")
ylim(1, 5.5)
theme(
axis.line.x = element_blank(),
axis.ticks.x = element_blank(),
axis.text.x = element_blank(),
axis.title.x = element_blank()
)
p1 <- p
xlim(1, 1.375)
geom_text_repel(
force = 0.5,
nudge_x = 0.15,
direction = "y",
hjust = 0,
segment.size = 0.2
)
ggtitle("hjust = 0")
p2 <- p
xlim(1, 1.375)
geom_text_repel(
force = 0.5,
nudge_x = 0.2,
direction = "y",
hjust = 0.5,
segment.size = 0.2
)
ggtitle("hjust = 0.5 (default)")
p3 <- p
xlim(0.25, 1)
scale_y_continuous(position = "right")
geom_text_repel(
force = 0.5,
nudge_x = -0.25,
direction = "y",
hjust = 1,
segment.size = 0.2
)
ggtitle("hjust = 1")
## Scale for y is already present.
## Adding another scale for y, which will replace the existing scale.
p1 p2 p3
也可以通过不同的图层在同一幅图中向左或向右排列标签：
代码语言：javascript复制set.seed(42)
dat <- subset(mtcars, wt > 2.75 & wt < 3.45)
dat$car <- rownames(dat)
ggplot(dat, aes(wt, mpg, label = car))
geom_text_repel(
data = subset(dat, wt > 3),
nudge_x = 3.5 - subset(dat, wt > 3)$wt,
segment.size = 0.2,
segment.color = "grey50",
direction = "y",
hjust = 0
)
geom_text_repel(
data = subset(dat, wt < 3),
nudge_x = 2.7 - subset(dat, wt < 3)$wt,
segment.size = 0.2,
segment.color = "grey50",
direction = "y",
hjust = 1
)
scale_x_continuous(
breaks = c(2.5, 2.75, 3, 3.25, 3.5),
limits = c(2.4, 3.8)
)
geom_point(color = "red")
可以看到，ggrepel 包为避免图上文本间的重叠提供了很好的解决方案，使我们能够轻松地在图上添加各种文本内容。
