"R scientific data" in Chapter 21 mainly explain how to use ggplot2 draw "good graphics", this note include "tags" and "Comment" in two parts.
1. Label
#v0
ggplot(mpg, aes(displ, hwy)) + geom_point(aes(color = class)) + geom_smooth(se = FALSE)
#v1
ggplot(mpg, aes(displ, hwy)) + geom_point(aes(color = class)) + geom_smooth(se = FALSE) + labs(
title = "Fuel efficiency generally decreases with engine size",
subtitle = "Two seaters (sports cars) are an exception because of their light weight",
caption = "Data from fueleconomy.gov",
x = "Engine displacement (L)",
y = "Highway fuel economy (mpg)",
colour = "Car type"
)
When the label contains a mathematical formula?
#?plotmath 查看一些基本数学公式的表示方法
df <- tibble(
x = runif(10),
y = runif(10)
)
ggplot(df, aes(x, y)) + geom_point() + labs(x = quote(sum(x[i] ^ 2, i ==1, n)), y = quote(alpha + beta + frac(delta, theta)))
2. Comment
"More details of the text label"
best_in_class <- mpg %>% group_by(class) %>% filter(row_number(desc(hwy)) == 1) #按照class分组，每一组依次filter；desc()表示降序排列；row_number()表示第几行
ggplot(mpg, aes(displ, hwy)) + geom_point(aes(color = class)) + geom_text(aes(label = model), data = best_in_class)
#图片如下，存在文本标签重叠以及文本掩盖了点的情况
ggplot(mpg, aes(displ, hwy)) + geom_point(aes(color = class)) + geom_label(aes(label = model), data = best_in_class, nudge_y = 2, alpha = 0.5) #nudge_y = 2表示文本框向上移2个单位
#图片如下，文本框重叠，不能明确文本框指代的是哪一个点
ggplot(mpg, aes(displ, hwy)) + geom_point(aes(color = class)) + geom_point(size = 3, shape = 1, data = best_in_class) + ggrepel::geom_label_repel(aes(label = model), data = best_in_class, size = 4, label.size = 1, segment.color = "green")
#优点：
#第二个geom_point()函数勾出了文本框指代的点，与geom_label_repel()函数搭配使用效果更好；
#同时geom_label_repel()可以错开原来重叠的文本框；
#size文本框中字体大小；
#label.size文本框粗细；
#segment.color左上角指代线段的颜色
text_cor <- tibble(displ = Inf, hwy = Inf)
ggplot(mpg, aes(displ, hwy)) + geom_point() + geom_text(data = text_cor, aes(label = "Increasing engine size is \nrelated to decreasing fuel economy."), vjust = "top", hjust = "right")
hjust vjust and a total of 9 combinations aligned, as follows
Other comments function
#如何添加参考线，并使参考线位于拟合线的下方（调整图层顺序即可）
p <- ggplot(mpg, aes(displ, hwy)) + geom_point(aes(color = class)) +
geom_hline(yintercept = 40, size = 1, color = "grey") +
geom_vline(xintercept = 6, size = 1, color = "grey") +
geom_smooth(se = FALSE)
#如何添加箭头
arrow_cor <- tibble(xend = c(5.3, 5.7), yend = c(25, 26), x = c(5.1, 5.9), y = c(27, 28))
p + geom_segment(data = arrow_cor, aes(x = x, y = y, xend = xend, yend = yend), arrow = arrow(length = unit(0.1, "inches")))
总结: Which functions can add comments (including text, lines, arrows)
geom_text (), geom_label (), ggrepel :: geom_label_repel (), geom_hline (), geom_vline (), geom_segment (arrow arrow = ...)
Reproduced in: https: //www.jianshu.com/p/3c7534750a86