如何在 R 中绘制手动色标？

Question

我正在 R 中使用 plotly 制作 3D 曲面图，如下所示；

#create dataframe
df <-data.frame(x = c(rnorm(300, 3, 2.5), rnorm(150, 7, 2)), # create random data
                  y = c(rnorm(300, 6, 2.5), rnorm(150, 2, 2)),
                  z = c(rnorm(300, 6, 2.5), rnorm(150, 2, 2)))

#prepare surface and plot
s = interp(x = df$x, y = df$y, z = df$z,duplicate = "mean") # prepare for plot_ly plot
p <- plot_ly(x = s$x, y = s$y, z = s$z,colorscale = 'RdYlBu')%>% # plot_ly
    add_surface()

，结果如下图；

在这里，我想将 "color transition from blue to red" 设置为 z = 2.5。

有什么方法可以巧妙地做到这一点吗？

虽然我现在用的是colorscale = 'RdYlBu'，但不一定要用。无论如何，理想的颜色模式是在 z = 2.5 处将 "color transition" 置于蓝色和红色之间，因为它可以在 ggolot2 中手动实现，如下所示；

gg <-ggplot(df, aes(x=x, y=y, color=z)) + 
   geom_point() + 
   scale_color_gradient2(midpoint=2.5, low="blue", mid="white",high="red", space ="Lab")

，结果如下图；

您有什么解决方案建议吗？

Answer 1

library(plotly)
library(akima)

df <-data.frame(x = c(rnorm(300, 3, 2.5), rnorm(150, 7, 2)), # create random data
                y = c(rnorm(300, 6, 2.5), rnorm(150, 2, 2)),
                z = c(rnorm(300, 6, 2.5), rnorm(150, 2, 2)))

s <- interp(x = df$x, y = df$y, z = df$z, duplicate = "mean") 

t <- (2.5 - min(df$z)) / (max(df$z) - min(df$z))

plot_ly(x = s$x, y = s$y, z = s$z) %>% 
  add_surface(colorscale = list(list(0,"blue"), list(t,"white"), list(1,"red")))

如何在 R 中绘制手动色标？

How to make manual colorscale in plotly in R?

r

colors

ggplot2

plotly

r-plotly