Character vector of length 1 all but the first element will be ignored error when filtering data in Shiny Application

问题

I have the following Shiny Application:

library(shiny)
library(rhandsontable)
library(shinydashboard)
library(ggplot2)
library(dplyr)

setwd("C:/Users/Marc/Dropbox/PROJECTEN/Lopend/shiny_interactive_graph")

tweets <- data.frame(
  city = c("new york", "texas", "texas"),
  tweet = c("Test1", "Test", "tst")
)


shinyApp(
  ui = dashboardPage(
    dashboardHeader(
      title = "Tweetminer",
      titleWidth = 350
    ),
    dashboardSidebar(
      width = 350,
      sidebarMenu(
        menuItem("Menu Item")
      )
    ),
    dashboardBody(
      fluidRow(
        tabBox(
          tabPanel("Set tweets2", 
                   plotOutput('plot',
                              brush = brushOpts(
                                id = "plot1_brush"
                              )),
                   h4("Selected States"),
                   verbatimTextOutput("select_states"),
                   h4("Selected States' Tweets"),
                   verbatimTextOutput("tweets")
          )
        )
      )
    )
  ),
  server = function(input, output) { 

    output$plot <- renderPlot({

      all_states <- map_data("state") 
      # Add more states to the lists if you want
      states_positive  <-c("new york")
      states_negative  <- c("texas")
      # Plot results
      ggplot(all_states, aes(x=long, y=lat, group = group)) +
        geom_polygon(fill="grey", colour = "white") +
        geom_polygon(fill="green", data = filter(all_states, region %in% states_positive)) +
        geom_polygon(fill="red", data = filter(all_states, region %in% states_negative))

    })

    selected_points <- reactiveVal()

    observeEvent(input$plot1_brush,{
      all_states <- map_data("state")
      selected_points( brushedPoints(all_states, input$plot1_brush))
    })

    observeEvent(selected_points(), {
      showModal(modalDialog(
        title = "Important message",
        tweets[(tweets$city %in% brushed_states()),],
        easyClose = TRUE
      ))
    })

    output$brush_info <- renderPrint({
      all_states <- map_data("state")
      brushedPoints(all_states, input$plot1_brush)
    })

    #get states from brushed coordinates
    brushed_states <- reactive({
      all_states <- map_data("state")
      brushed <- brushedPoints(all_states, input$plot1_brush)
      unique(brushed$region)
    })

    #this is to show the selected states
    output$select_states <- renderText({
      brushed_states()
    })

    output$tweets <- renderPrint({
      tweets[(tweets$city %in% brushed_states()),]
    })


  })

This basically allows to select a map on the map and then get a popup with all the relevant tweets. I fetch the relevant tweets by this line:

tweets[(tweets$city %in% brushed_states()),]

However, when I select Texas I only get his:

texas Test

While I expect:

texas Test
texas tst

I think this has to do with the following error:

Warning in charToRaw(enc2utf8(text)) :
argument should be a character vector of length 1
all but the first element will be ignored

I am kind of lost, what is exactly happening here.... Any thoughts on what is causing this error?

回答1:

The reason it does not work is that the modalDialog expects text or html, but you are passing it a data.frame, which it does not know how to print. So you have to convert your data.frame to a printable version first. Here is an example implementation:

    observeEvent(selected_points(), {
      my_tweets <- tweets[(tweets$city %in% brushed_states()),]
      showModal(modalDialog(
        title = "Important message",
        HTML(paste(apply(my_tweets,1,function(x) {paste(x,collapse=': ')}),collapse='<br>')),
        easyClose = TRUE
      ))
    })

Hope this helps!

来源：https://stackoverflow.com/questions/48383010/character-vector-of-length-1-all-but-the-first-element-will-be-ignored-error-whe