Get row number from of data point from event_data - r

Question

I have been creating a data viewer app using shiny and plotly. I want to make a create a multi dimensional scaling view of my data, and then click on a data point to be able to view the individual point as a barplot. I was inspired by this example.
Here is a minimal almost working example:
The ui.r file
library(shiny)
library(mlbench)
library(plotly)
library(shinythemes)
library(dplyr)
# Load the data
allDat <- iris[,-5]
# ui.R definition
ui <- fluidPage(
# Set theme
theme = shinytheme("spacelab"),
# Some help text
h2("Inspect each element in iris data set"),
h4("This a shiny app exploiting coupled events in plotly"),
tags$ol(
tags$li("The first chart showcases", tags$code("plotly_click"))
),
# Vertical space
tags$hr(),
# First row
fixedRow(
column(6, plotlyOutput("Plot1", height = "600px")),
column(6, plotlyOutput("Plot2", height = "600px"))),
tags$hr())
The server.r file
# server.R definition
server <- function(input, output){
d <- dist(allDat) # euclidean distances between the rows
fit <- cmdscale(d,eig=TRUE, k=2) # k is the number of dim
# plot solution
x <- fit$points[,1]
y <- fit$points[,2]
plot.df <- data.frame(x=x,y=y,allDat)
output$Plot1 <- renderPlotly({
plot_ly(plot.df, x = x, y = y, mode="markers", source = "mds") %>%
layout(title = "MDS of iris data",
plot_bgcolor = "6A446F")
})
# Coupled event 2
output$Plot2 <- renderPlotly({
# Try to get the mouse click data
event.data <- event_data("plotly_click", source = "mds")
# If NULL dont do anything
if(is.null(event.data) == T) return(NULL)
# I need the row of the data in the allDat data frame
# pretty sure this is not correct
ind <- as.numeric(event.data[2])
p1 <- plot_ly(x = colnames(allDat), y=as.numeric(allDat[ind,]),type="bar")
})
}
To run this, put these two files in a folder called something, e.g. dataViewer, then run runApp("dataViewer") from the directory that contains the dataViewer folder.
What is the question and what am I seeking?
I do not understand the output that comes from the event_data function. I want to be able to click on a point on the scatter plot and extract the row number of that data point from the allDat data frame, or the plot.df data frame, because it should be the same. Then I want to use that row number to further visualize that specific point in the barplot on the right.

Answer 1

I looked into the event.data object, and think the value you are looking for is event.data$pointNumber (which starts with 0 so you need to use event.data$pointNumber + 1 to identify the line).
event.data is a list with four names: curveNumber, pointNumber, x and y.