Shiny Parallel Coordinates with Brushing and Linking - r

Question

I'm creating a flexdashboard / Shiny app in R using Rstudio and am trying to create a dashboard with two components: a parallel coordinates graph on top and a table below the graph.
I'm trying to use Brushing and Linking to select specific axis in the parallel coordinate graph to affect and filter data in the table.
Below is my code (adapted from https://jjallaire.shinyapps.io/shiny-ggplot2-brushing/):
---
title: "ggplot2 Brushing"
output:
flexdashboard::flex_dashboard:
orientation: columns
social: menu
source_code: embed
runtime: shiny
---
```{r global, include=FALSE}
# load data in 'global' chunk so it can be shared by all users of the dashboard
library(datasets)
mtcars2 <- mtcars[, c("mpg", "cyl", "wt")]
```
```{r}
# Reactive that returns the whole dataset if there is no brush
selectedData <- reactive({
data <- brushedPoints(mtcars2, input$plot1_brush)
if (nrow(data) == 0)
data <- mtcars2
data
})
```
Column {data-width=650}
-----------------------------------------------------------------------
### Miles Per Gallon vs. Weight {data-width=600}
```{r}
library(ggplot2)
library(GGally)
plotOutput("plot1", brush = brushOpts(id = "plot1_brush"))
output$plot1 <- renderPlot({
ggparcoord(mtcars2) + geom_line()
})
```
### Car Details {data-width=400}
```{r}
renderTable({
selectedData()
}, rownames = TRUE)
```
As you can see, brushing and linking are not working. What am I missing here? I've read a few questions about the topic and particularly around XY variables and only working for scatterplots, etc. But certainly there is a way around this and I can't seem to find a solution. Does anybody have an idea on how to make brushing and linking work with parallel coordinates in Shiny?

Answer 1

I have tried to find solution to Your problem but actually it is not possible at this moment to retrieve the data using brush from any parallel coordinates plot (neither plotly or ggplot2). You can easily use the brush in plotly, but You will not be able to get the data out of it (in Your case it is selectedData()). Maybe You should try another plot type.