R语言之可视化（20）之geom_label（）和geom_text（）

Geom_text（）将文本直接添加到绘图中。 geom_label（）在文本后面绘制一个矩形，使其更易于阅读。

示例

p <- [ggplot](mtcars, aes(wt, mpg, label = rownames(mtcars)))
p + geom_text()

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避免字体重叠

p + geom_text(check_overlap = TRUE)

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给label加上背景

p + geom_label()

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修改字体大小

p + geom_text(size = 10)

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p + geom_point() + geom_text(hjust = 0, nudge_x = 0.05)

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p + geom_point() + geom_text(vjust = 0, nudge_y = 0.5)

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p + geom_point() + geom_text(angle = 45)

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添加映射

p + geom_text(aes(colour = factor(cyl)))

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p + geom_text(aes(colour = factor(cyl))) + scale_colour_discrete(l = 40)

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p + geom_label(aes(fill = factor(cyl)), colour = "white", fontface = "bold")

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p + geom_text(aes(size = wt))

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缩放文本高度

p + geom_text(aes(size = wt)) + scale_radius(range = c(3,6))

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可以通过设置parse = TRUE来显示表达式。themama中描述了显示的详细信息，但请注意geom_text使用字符串，而不是表达式。

p + geom_text(aes(label = paste(wt, "^(", cyl, ")", sep = "")), parse = TRUE)

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添加一个注释

p +geom_text() +annotate("text", label = "plot mpg vs. wt", x = 2, y = 15, size = 8, colour = "red")

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对齐标签和条形

df <- data.frame( x = factor(c(1, 1, 2, 2)), y = c(1, 3, 2, 1), grp = c("a", "b", "a", "b") )

ggplot2不知道你想给标签赋予相同的虚拟宽度

ggplot(data = df, aes(x, y, group = grp)) + geom_col(aes(fill = grp), position = "dodge") + geom_text(aes(label = y), position = "dodge")

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ggplot(data = df, aes(x, y, group = grp)) + geom_col(aes(fill = grp), position = "dodge") + geom_text(aes(label = y), position = position_dodge(0.9))

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＃使用你无法轻推和躲避文字，所以改为调整y位置

ggplot(data = df, aes(x, y, group = grp)) + geom_col(aes(fill = grp), position = "dodge") + geom_text( aes(label = y, y = y + 0.05), position = position_dodge(0.9), vjust = 0 )

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如果将文本放在堆积的条形图中每个条形图的中间，需要设置position_stack（）的vjust参数

ggplot(data = df, aes(x, y, group = grp)) + geom_col(aes(fill = grp)) + geom_text(aes(label = y), position = position_stack(vjust = 0.5))

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