Translate plotmath expressions

I have 2 issues using function ggplotly in R:

Question 1 What are the ways to keep R plotmath expressions while converting ggplot2 plots to plotly format using function ggplotly?

Now the expressions are converted to [object Object] as in this example below:

library(ggplot2)
library(plotly)

qplot(mpg, wt, data = mtcars) +
    ggtitle(expression(bar(x) == sum(frac(x[i], n), i==1, n)))

ggplotly()

Question 2

How to get rid of double labels in the legend of plotly graph and make them look like in ggplot2 graph? I.e. how to get 6 in stead of (6,6):

qplot(mpg, wt, data = mtcars, colour = as.factor(cyl), fill = as.factor(cyl))

ggplotly()

首先使用 ggplot2 和 ggplotly 重现报告的两个示例：plotmath 标题变成 [object Object]，并且图例显示重复的值，例如 (6,6)。跟踪 ggplotly 如何转换 plotmath 表达式和组合的 colour/fill 标度，然后验证表达式是否能正确渲染，以及图例条目是否与 ggplot2 的结果一致。