Using brushedPoints with custom coord transformation.

Shiny
1

I am having trouble selecting points using a brush when I use a custom axis-transformation. I have pasted a snippet of code below. Basically the app works as expected, when I don't use transformation but not with asinh transformation.

library(ggplot2)

shinyApp(
  ui = fluidPage(
    selectInput(inputId = 'axis_trans',
                label = 'Transform Axis: ',
                choices = list("None", "log2", "asinh")
    ),
    plotOutput("bPlot", brush=brushOpts("bBrush")),
    fluidRow( column(5, "Brushed: ", verbatimTextOutput( "brushed" )))
    
  ),
  
  server = function(input, output, session) {
    asinhco_trans <- function(cofactor) {
      require(scales)
      trans_new("asinhco", 
                transform=function(x) {
                  if (cofactor !=0) {
                    xt <- asinh(x/cofactor)
                  } else {
                    xt <- asinh(x)
                  }
                  return(xt)
                },
                inverse= function(xt) {
                  if (cofactor != 0) {
                    x <- cofactor*sinh(xt)
                  } else {
                    x <- sinh(xt)
                  }
                  return(x)
                }
      )
    }
    output$bPlot <- renderPlot({
      p <- ggplot( mtcars, aes_string( x="mpg", y="wt") ) + geom_point() 
      if (input$axis_trans == "asinh") {
        p <- p + coord_trans(x=asinhco_trans(10), y=asinhco_trans(10))
      }
      if (input$axis_trans == "log2") {
        p <- p + coord_trans(x="log2", y="log2")
      }
      return(p)
    })
    output$brushed <- renderText({
      nrow(brushedPoints(mtcars,input$bBrush))
    })
  }
  
)
2

I was able to solve this by applying the transformation directly to the data, instead of the axis.

3

Would you mind sharing the code you have used to solve your problem and markin your post as a solution to your topic? This could be helpful to other people facing the same problem.