clicking on a point in dygraph in Shiny and printing out its corresponding date in POSIXct

Question

I would like to click on a point in dygraph and get its corresponding date in "%Y-%m-%d %H:%M:%S" format. Here I've reproduced my problem:

library(dygraphs)
library(tidyverse)
library(data.table)
library(shiny)


dates <- seq(as.POSIXct("2021-01-01 05:00:00"), as.POSIXct("2021-01-05 05:00:00"), by = 8*3600)

set.seed(24)

df <- data.table(date = dates,
                 percentage = round(runif(length(dates), min = 0, max = 1), digits = 2)
                 )


ui <- fluidPage(
  fluidRow(
    column(width = 12,
           dygraphOutput("dygraph")
    )
  ),
  fluidRow(
    verbatimTextOutput("click")
  )
)

server <- function(input, output){
  
  output$dygraph <- renderDygraph({
    dygraph(df) 
  })
  
  output$click <- renderPrint({
    input$dygraph_click$x
  })
}

shinyApp(ui = ui, server = server)

Here is how the output looks like:

My problem is that it doesn't give me the right format. I tried to use the format function, but it did not work. I used the following line inside my renderprint:

format(as.POSIXct(input$dygraph_click$x), "%Y-%m-%d %H:%M:%S")

And here is the output:

It does not show the hour:minute:second properly.

Does anyone know how I can print out the POSIXct format of a date upon clicking on its corresponding point? I would appreciate any help.

Answer 1

You can use lubridate::ymd_hms to convert input$dygraph_click$x in POSIXct format and use format to display the output.

output$click <- renderPrint({
    format(lubridate::ymd_hms(input$dygraph_click$x, tz = Sys.timezone()))
  })

Complete code -

library(dygraphs)
library(tidyverse)
library(data.table)
library(shiny)

dates <- seq(as.POSIXct("2021-01-01 05:00:00"), 
             as.POSIXct("2021-01-05 05:00:00"), by = 8*3600)

set.seed(24)

df <- data.table(date = dates,
                 percentage = round(runif(length(dates), min = 0, max = 1), digits = 2)
)

ui <- fluidPage(
  fluidRow(
    column(width = 12,
           dygraphOutput("dygraph")
    )
  ),
  fluidRow(
    verbatimTextOutput("click")
  )
)

server <- function(input, output){
  
  output$dygraph <- renderDygraph({
    dygraph(df) 
  })
  
  output$click <- renderPrint({
    format(lubridate::ymd_hms(input$dygraph_click$x, tz = Sys.timezone()))
  })
}

shinyApp(ui = ui, server = server)