合并单独的几何图层的图例

时间:2018-06-29 11:01:33

标签: r ggplot2 gis legend

我正在绘制地图上两个独立图层的点数据,并希望在一个图例中显示两个图层的信息。

下面是一些说明问题的代码:

set.seed(42)  
lat1 <- rnorm(10, 54, 12)
long1 <- rnorm(10, 44, 12)
val1 <- rnorm(10, 10, 3)
lat2 <- rnorm(10, 54, 12)
long2 <- rnorm(10, 44, 12)
val2 <- rnorm(10, 10, 3)

df1 <- as.data.frame(cbind(long1, lat1, val1))
df2 <- as.data.frame(cbind(long2, lat2, val2))

library(ggplot2)
library(scales)

f <- ggplot() +
     geom_point(data=df1, aes(x=lat1, y=long1, size=val1, fill=val1), shape=21, alpha=0.6) +
     scale_size_continuous(range = c(2, 12), breaks=pretty_breaks(4)) +
     scale_fill_distiller(direction = -1, palette="RdYlBu", breaks=pretty_breaks(4)) +     
     guides(fill = guide_legend(), size = guide_legend()) +
     theme_minimal()
p <- f + geom_point(data=df2, aes(x=lat2, y=long2, color="val2"), shape=17, size=3) +
     scale_color_manual(values="black",name="")
p

我能管理的最好的办法是创建两个单独的图例,然后删除其中一个图例标题。理想情况下,实心圆圈和黑色菱形都应属于同一个图例,例如“价值”和黑色菱形将显示为“ NA”。任何帮助深表感谢!

1 个答案:

答案 0 :(得分:2)

我们必须绘制两个不同的图例,但将它们彼此靠近(在legend.spacing.y中使用负值需要ggplot2_3.0.0)。这种方法带来了另一个问题-两个图例无法对齐,因此我们必须绘制另一组菱形(较大以匹配非菱形,但看不见的alpha = 0

ggplot() +
    geom_point(data = df1, 
               aes(lat1, long1, size = val1, fill = val1), 
               shape = 21, alpha = 0.6) +
    geom_point(data = df2, 
               aes(lat2, long2, color = "val2"), 
               shape = 17, size = 3) +
    geom_point(data = df2, 
               aes(lat2, long2, color = "val2"), 
               shape = 17, size = 11.5, alpha = 0) +
    scale_size_continuous(range = c(2, 12), breaks = pretty_breaks(4)) +
    scale_fill_distiller(direction = -1, palette = "RdYlBu", breaks = pretty_breaks(4)) +     
    scale_color_manual(values = "black", name = "Value\n") +
    labs(fill = NULL,
         size = NULL) +
    guides(fill = guide_legend(), 
           size = guide_legend(),
           color = guide_legend(order = 1)) +
   theme_minimal() +
   theme(legend.spacing.y = unit(-0.4, "cm"))

enter image description here