Soy nuevo en shiny y estaba tratando de escribir una aplicación donde el usuario pueda agregar dinámicamente filtros de datos (vea el código a continuación). Pensé que insertUI y remove UI son geniales para ese propósito. Sin embargo, tengo varios problemas:

    1) I cannot address dynamically generates input$ids (see filterId in the code, l. 36 and l. 58)
    2) in updateCheckboxGroupInput (l. 62) checkboxes are not preselected.
    3) I cannot select data rows using which() (l. 74)
    4) The checkboxes are not displayed inside the column, but spread over the whole page.

Aprecio mucho cualquier pista.

Gracias Jordi

aqui el codigo:

library(shiny)

rowvalues <- function(col,data) {
  as.list(unique(data[col]))
}

ui <- fluidPage(
  sidebarLayout(
    sidebarPanel(
      fluidRow(
        column(6, actionButton('addFilter', 'Add filter')),
        column(6, actionButton('removeFilter', 'Remove filter')),
        offset = 6
      ),
      tags$hr(),
      tags$div(id = 'placeholderAddRemFilt'),
      tags$div(id = 'placeholderFilter'),
      width = 4 # sidebar
    ),
    mainPanel(
      tableOutput("data")
    )
  )
)

server <- function(input, output,session) {
  filter <- character(0)

  observeEvent(input$addFilter, {
    add <- input$addFilter
    filterId <- paste0('Filter', add)
    headers <- names(mtcars)
    insertUI(
      selector = '#placeholderFilter',
      ui = tags$div(
        # selectInput(filterId, label = paste0("Filter ",add), # does not work
        selectInput("ColFilter", label = paste0("Filter ",add), 
                    choices = as.list(headers), 
                    selected = 1),
        checkboxGroupInput("RowFilter", label = "Select variable values",
                           choices = NULL, selected = NULL, 
                           inline = TRUE, width = 4000),
        id = filterId
      )
    )

    filter <<- c(filter,filterId)
  })

  observeEvent(input$removeFilter, {
    removeUI(
      ## pass in appropriate div id
      selector = paste0('#', filter[length(filter)])
    )
    filter <<- filter[-length(filter)]
  })

  # observeEvent(input$filterId, { # does ntót work
  observeEvent(input$ColFilter, {
    col <- input$ColFilter
    values <- as.list(unique(mtcars[col]))[[1]]
    updateCheckboxGroupInput(session,"RowFilter", label = "Select variable    values", 
                              choices = values, selected = values, 
                              inline = TRUE)
  })

  output$data <- renderTable({
    col <- input$ColFilter
    rows <- input$RowFilter
    print(c("selected col: ",col))
    print(c("selected rows: ",as.vector(rows)))
    if(is.null(col)) mtcars
    else {
      mtcars[which(mtcars$col != rows),]
    }
  })
 }

shinyApp(ui = ui, server = server)