R语言ggplot2图例修改超详细介绍

时间:2022-11-05 医学和生信笔记人气:0

前言

大家经常对ggplot2中的图例不满意，想要各种修改，今天就介绍下图例的各种修改细节，基本上常用的操作都涉及到了！

library(ggplot2)
library(gcookbook)

移除图例

提供3种方法可以在ggplot2中移除图例。

# 基本图形
pg_plot <- ggplot(PlantGrowth, aes(x = group, y = weight, fill = group)) +
  geom_boxplot()

pg_plot

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# 首先可以使用guides()函数移除图例
pg_plot +
  guides(fill = "none")

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然后可以在scale_**函数中移除，这里是fill，你要根据自己的情况换成shape、color等。

pg_plot+scale_fill_discrete(guide = "none")

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第3种方法是在theme中移除。

pg_plot+theme(legend.position = "none")

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改变图例位置

也是在theme中更改，

pg_plot <- ggplot(PlantGrowth, aes(x = group, y = weight, fill = group)) +
  geom_boxplot() +
  scale_fill_brewer(palette = "Pastel2")

pg_plot +
  theme(legend.position = "top") # 放在顶部

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legend.position的参数可以是left、right、top、bottom，还可以是坐标。

pg_plot+theme(legend.position = c(0.8,0.3))

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在ggplot2中，左下角的坐标是c(0,0)，右上角的坐标是c(1,1),你可以自己设置想要放置的位置。需要注意的是，你设置的这个坐标是图例中心点的坐标，可以通过legend.justification设置图例的哪个位置放在你的坐标上。

# 图例右下角，放在画布右下角
pg_plot +
  theme(legend.position = c(1, 0), legend.justification = c(1, 0))

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p <- ggplot(heightweight, aes(x=ageYear, y=heightIn, shape=sex, colour=sex))+geom_point()
p

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两个图例更改为水平排列：

p + scale_shape_discrete(label = c("female","male")) +
  theme(legend.direction = "horizontal")

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修改图例的边框和背景

pg_plot+
  theme(legend.position = c(0.85,0.2))+
  theme(legend.background = element_rect(fill = "orange",color = "black"))

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中间还有一部分是白色，需要另外一个参数修改：

pg_plot+
  theme(legend.position = c(0.85,0.2))+
  theme(legend.background = element_rect(fill = "orange",color = "black"),
        legend.key = element_rect(fill = "orange")
        )

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改变图例顺序

pg_plot <- ggplot(PlantGrowth, aes(x = group, y = weight, fill = group)) +
  geom_boxplot()

pg_plot

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# limits
pg_plot +
  scale_fill_discrete(limits = c("trt1", "trt2", "ctrl"))

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也可以在画图之前，通过因子化的方法把数据先排好序再画图哦。

反转图例顺序

2种方法。

pg_plot+scale_fill_discrete(guide = guide_legend(reverse = T))

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pg_plot+guides(fill = guide_legend(reverse = T))

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修改图例标题

2种方法。

pg_plot <- ggplot(PlantGrowth, aes(x = group, y = weight, fill = group)) +
  geom_boxplot()

pg_plot

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labs里面修改

pg_plot + labs(fill = "Condition")

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在scale_*函数里面修改。

pg_plot+scale_fill_discrete(name = "hahah")

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还有一种比较复杂的情况，如果多个一个变量映射给多个图形参数，或者有多个图例，怎么修改呢？像下面这个例子，sex和shape、color都有关。

p <- ggplot(heightweight, aes(x=ageYear, y=heightIn, shape=sex, colour=sex))+geom_point()
p

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可以在scale_*函数中修改：

p + scale_shape_discrete(name = "shape")+
  scale_color_discrete(name = "colooorrr")

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也可以在legend中修改：

p + labs(shape = "shapppeee",color = "colooorrr")

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还可以在guides函数中修改：

p + guides(shape = guide_legend(title = "this is\nshape"),
           color = guide_legend(title = "cooolor")
           )

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修改图例标题外观

pg_plot <- ggplot(PlantGrowth, aes(x = group, y = weight, fill = group)) +
  geom_boxplot()
pg_plot

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可以在theme中修改:

pg_plot + theme(
  legend.title = element_text(
    face = "italic",
    family = "Times",
    colour = "red",
    size = 18
  )
)

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也可以在guides中修改：

pg_plot +
  guides(fill = guide_legend(title.theme = element_text(
    face = "italic",
    family = "Times",
    colour = "red",
    size = 14))
  )

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移除图例标题

pg_plot

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可以在theme中修改，也可以在scale_xxx函数中修改，也可以在guides函数中修改。

pg_plot+theme(legend.title = element_blank())

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pg_plot+scale_fill_discrete(name = NULL)

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pg_plot+scale_fill_hue(guide = guide_legend(title = NULL))

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pg_plot+guides(fill = guide_legend(title = NULL))

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修改图例标签

pg_plot

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pg_plot+scale_fill_discrete(labels = c("label1","label2","label3"))

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修改图例标签外观

在theme中修改：

pg_plot +
  theme(legend.text = element_text(
    colour = "red",
    face = "italic",
    size = 22)
  )

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总结

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