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)
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
# 首先可以使用guides()函数移除图例 pg_plot + guides(fill = "none")
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")
第3种方法是在theme中移除。
pg_plot+theme(legend.position = "none")
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
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))
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))
p <- ggplot(heightweight, aes(x=ageYear, y=heightIn, shape=sex, colour=sex))+geom_point() p
两个图例更改为水平排列：
p + scale_shape_discrete(label = c("female","male")) +
theme(legend.direction = "horizontal")
pg_plot+ theme(legend.position = c(0.85,0.2))+ theme(legend.background = element_rect(fill = "orange",color = "black"))
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")
)
pg_plot <- ggplot(PlantGrowth, aes(x = group, y = weight, fill = group)) + geom_boxplot() pg_plot
# limits
pg_plot +
scale_fill_discrete(limits = c("trt1", "trt2", "ctrl"))
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。
2种方法。
pg_plot+scale_fill_discrete(guide = guide_legend(reverse = T))
pg_plot+guides(fill = guide_legend(reverse = T))
2种方法。
pg_plot <- ggplot(PlantGrowth, aes(x = group, y = weight, fill = group)) + geom_boxplot() pg_plot
labs里面修改
pg_plot + labs(fill = "Condition")
在scale_*函数里面修改。
pg_plot+scale_fill_discrete(name = "hahah")
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
可以在scale_*函数中修改：
p + scale_shape_discrete(name = "shape")+ scale_color_discrete(name = "colooorrr")
也可以在legend中修改：
p + labs(shape = "shapppeee",color = "colooorrr")
还可以在guides函数中修改：
p + guides(shape = guide_legend(title = "this is\nshape"),
color = guide_legend(title = "cooolor")
)
pg_plot <- ggplot(PlantGrowth, aes(x = group, y = weight, fill = group)) + geom_boxplot() pg_plot
可以在theme中修改:
pg_plot + theme(
legend.title = element_text(
face = "italic",
family = "Times",
colour = "red",
size = 18
)
)
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))
)
pg_plot
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())
pg_plot+scale_fill_discrete(name = NULL)
pg_plot+scale_fill_hue(guide = guide_legend(title = NULL))
pg_plot+guides(fill = guide_legend(title = NULL))
pg_plot
pg_plot+scale_fill_discrete(labels = c("label1","label2","label3"))
在theme中修改：
pg_plot +
theme(legend.text = element_text(
colour = "red",
face = "italic",
size = 22)
)
