如何添加一条回归线到闪亮的rCharts图

Question

我试图在一个闪亮的应用程序中使用rCharts添加一条回归线到一个简单的散点图，但我不能让它工作。如果删除p$layer()调用，下面的代码可以很好地显示图形(没有回归线)。使用它，图形的轴被隐藏，并且没有线，尽管点仍然显示。我做错了什么?

谢谢你的帮助。

output$kplot = renderChart({
     # Create dependency on submit button.
     input$submit
     # Add point when submit button is clicked.
     dataset = isolate(rbind(dataset, c(input$add_x, input$add_y)))
     # Re-fit data.
     dataset$fit = lm(dataset$mpg ~ dataset$hp)$fitted.values
     # Calculate graph minimums and maximums
     xmin = max(min(dataset$hp) - 10, 0) # Cut threshold at zero.
     xmax = (max(dataset$hp) + 11) + (50 - ((max(dataset$hp) + 10) %% 50))
     ymin = 0
     ymax = (max(dataset$mpg) + 1) + (5 - ((max(dataset$mpg) + 5) %% 5))
     p = rPlot(mpg ~ hp, data=dataset, type="point")
     p$addParams(dom="kplot")
     p$guides(
        x = list(
           min = xmin,
           max = xmax,
           numticks = xmax / 50 + 1,
           title = "HP"
        ),
        y = list(
           min = ymin,
           max = ymax,
           numticks = ymax / 5 + 1,
           title = "MPG"
        )
     )
     p$layer(y=dataset$fit, copy_layer=T, type="line", color=list(const="red"))
     return(p)
  })

Answer 1

请检查下面我从@ramnathv的github复制的代码

https://gist.github.com/ramnathv/7576061

require(ggplot2)
require(rCharts)
dat = fortify(lm(mpg ~ wt, data = mtcars))
names(dat) = gsub('\.', '_', names(dat))
p1 <- rPlot(mpg ~ wt, data = dat, type = 'point')
p1$layer(y = '_fitted', copy_layer = T, type = 'line',
  color = list(const = 'red'),
  tooltip = "function(item){return item._fitted}")
p1