使用渐变按组对散点图进行颜色编码

Question

我有XY我想使用曲线图的数据scatter plot,用R的plotly包.

set.seed(1)
df <- data.frame(x=c(rnorm(30,1,1),rnorm(30,5,1),rnorm(30,9,1)),
                 y=c(rnorm(30,1,1),rnorm(30,5,1),rnorm(30,9,1)),
                 group=c(rep("A",30),rep("B",30),rep("C",30)),score=runif(90,0,1))

每个点都分配给三个组中的一个(df$group)并且在该[0,1]范围内具有分数.

我正在寻找一种方法来绘制数据图形,使每组用不同颜色着色,但颜色(或强度)的阴影反映了分数.

所以我认为这会奏效:

library(dplyr)
library(plotly)

    plot_ly(marker=list(size=10),type='scatter',mode="markers",x=~df$x,y=~df$y,color=~df$score,colors=c("#66C2A5","#FC8D62","#8DA0CB")) %>%
  layout(xaxis=list(title="X",zeroline=F,showticklabels=F),yaxis=list(title="Y",zeroline=F,showticklabels=F))

但我得到:

如果我只是通过group以下颜色代码:

plot_ly(marker=list(size=10),type='scatter',mode="markers",x=~df$x,y=~df$y,color=~df$group,colors=c("#66C2A5","#FC8D62","#8DA0CB")) %>%
      layout(xaxis=list(title="X",zeroline=F,showticklabels=F),yaxis=list(title="Y",zeroline=F,showticklabels=F))

我明白了:

所以看起来它正在混合group颜色和score渐变.

我正在寻找的是有绿色的色调(比如从有色左下方组gray到darkgreen)对应于score(从低到高),与同为分别在橙色和蓝色,其他两组.

Answer 1

使用scales::colour_ramp您可以使用快速功能自行创建颜色.我不确定如何在每个组内发生不同的渐变.注意我在df$score = df$x + df$y这里用来使映射更明显.

make_colour_gradient = function(x, brewer_palette = "Greens") {
    min_x = min(x)
    max_x = max(x)
    range_x = max_x - min_x
    x_scaled = (x - min_x) / range_x

    # Chopping out first colour as it's too light to work well as a
    #   point colour
    colours = scales::brewer_pal("seq", brewer_palette)(5)[2:5]

    colour_vals = scales::colour_ramp(colours)(x_scaled)
    colour_vals
}

df$score = df$x + df$y

df = df %>%
    # Assign a different gradient to each group, these are the names
    #   of different palettes in scales::brewer_pal
    mutate(group_colour = case_when(
        group == "A" ~ "Greens",
        group == "B" ~ "Oranges",
        group == "C" ~ "Purples"
    )) %>%
    group_by(group) %>%
    mutate(point_colour = make_colour_gradient(score, first(group_colour)))


plot_ly(marker=list(size=10),type='scatter',mode="markers",
        x=~df$x,y=~df$y,color=~ I(df$point_colour)) %>%
    hide_colorbar() %>%
    layout(xaxis=list(title="X",zeroline=F,showticklabels=F),
           yaxis=list(title="Y",zeroline=F,showticklabels=F))

结果:

这确实会显示错误消息,但它们似乎并不重要？添加图例可能会很棘手.