添加一行二维密度图中的R使用GGPLOT2

Question

下面是哈德利韦翰的书2D密度图：

f2d <- with(faithful, MASS::kde2d(eruptions, waiting, 
            h = c(1, 10), n = 50)) 
df <- with(f2d, cbind(expand.grid(x, y), as.vector(z))) 
names(df) <- c("eruptions", "waiting", "density") 
erupt <- ggplot(df, aes(waiting, eruptions, fill = density)) + 
    geom_tile() + 
    scale_x_continuous(expand = c(0, 0)) + 
    scale_y_continuous(expand = c(0, 0)) 
erupt + scale_fill_gradient(limits = c(0, 0.04), low = "white", high = "black") 

我尝试绘图在此之上的行：

mydf <- data.frame(x=c(50,60,70),y=c(2,3,4)) 
erupt + scale_fill_gradient(limits = c(0, 0.04), low = "white", high = "black") + geom_line(aes(x=x,y=x), data = mydf) 

，但我得到了以下错误：

Error in data.frame(x = c(50, 60, 70), y = c(50, 60, 70), fill = function (x, : 
    arguments imply differing number of rows: 3, 0 

我不明白这是为什么。谢谢。

Answer 1

两个问题，首先是@aosmith说你需要在geom_tile中设置特定的审美密度。其次还有在geom_line(aes(x=x,y=x)

一个错字所以

erupt <- ggplot(df, aes(waiting, eruptions)) + 
    geom_tile(aes(fill=density)) + 
    scale_x_continuous(expand = c(0, 0)) + 
    scale_y_continuous(expand = c(0, 0)) 

mydf <- data.frame(x=c(50,60,70),y=c(2,3,4)) 
erupt + scale_fill_gradient(limits = c(0, 0.04), low = "white", high = "black") + 
    geom_line(aes(x=x,y=y), data = mydf) 

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