r语言 - 情节:如何根据值指定符号和颜色?

Question

在R中使用plotly进行绘图时，如何根据值指定颜色和符号？例如，对于mtcars示例数据集，如果mtcars$mpg大于或小于 18，如何绘制为红色方块？

例如：

library(plotly)

p <- plot_ly(type = "scatter", data = mtcars, x = rownames(mtcars), y = mtcars$mpg,
mode = "markers" )

如何将 20 以上的所有点都作为黄色方块？

Answer 1

你可以做这样的事情：

plot_ly(type = "scatter", data = mtcars, x = rownames(mtcars), y = mtcars$mpg,
mode = "markers", symbol = ~mpg > 20, symbols = c(16,15),
color = ~mpg > 20, colors = c("blue", "yellow"))

https://plot.ly/r/line-and-scatter/#mapping-data-to-symbols

是的，这是可能的，我会先用cut()在plot_ly()之外进行所有分组和形状/颜色规范。然后在引用新的颜色和形状变量时利用plot_ly()内部的文字I()语法：

data(mtcars)
mtcars$shape <- cut(mtcars$mpg,
breaks = c(0,18, 26, 100),
labels = c("square", "circle", "diamond"))
mtcars$color <- cut(mtcars$mpg,
breaks = c(0,18, 26, 100),
labels = c("red", "yellow", "green"))
plot_ly(type = "scatter", data = mtcars, x = rownames(mtcars), y = mtcars$mpg,
mode = "markers", symbol = ~I(shape), color = ~I(color))