Print str() of table in shiny dashboard - r

Question

I am a newbie to shiny dashboard. I want to know how to print str() of the table which i have imported in shiny dashboard. my code is not working. When i print str(), i get the below output,
str()
Please check the code which i have written,
library(shiny)
library(shinydashboard)
library(DT)
ui <- dashboardPage(
dashboardHeader(title = "Analytics Workbench 2.0", titleWidth = 250,
dropdownMenuOutput("msgs")),
dashboardSidebar(
sidebarMenu(
fileInput("Table1", "Train Data"),
fileInput("Table2", "Test Data"),
menuItem("Variable Analysis", icon = icon("edit"),
menuSubItem("Uni-Variate Analysis"),
menuSubItem("Multi-Variate Analysis"))
)
),
dashboardBody(
fluidRow(
column(12, box(title = "Train Data", width = 6, solidHeader = TRUE, status = "warning",
collapsible = TRUE, DT::DTOutput("Train")),
box(title = "Test Data", width = 6, solidHeader = TRUE, status = "warning",
collapsible = TRUE, DT::DTOutput("Test")))),
fluidRow(
column(12, box(title = "Structure", width = 6, solidHeader = TRUE, status = "warning",
collapsible = TRUE, verbatimTextOutput("str1")),
box(title = "Structure", width = 6, solidHeader = TRUE, status = "warning",
collapsible = TRUE, verbatimTextOutput("str2"))))
)
)
server <- function(input, output) {
output$msgs <- renderMenu({
msg <- apply(read.csv("messages.csv"), 1, function(row){
messageItem(from = row[["from"]], message = row[["message"]]) })
dropdownMenu(type = "messages", .list = msg)
})
output$Train <- DT::renderDT({
if (is.null(input$Table1)) return(NULL)
data1 <- read.table(input$Table1$datapath, fill = TRUE, header=T, sep=",")
DT::datatable(data1, options = list(scrollX = TRUE))
})
output$Test <- DT::renderDT({
if (is.null(input$Table2)) return(NULL)
data2 <- read.table(input$Table2$datapath, fill = TRUE, header=T, sep=",")
DT::datatable(data2, options = list(scrollX = TRUE))
})
output$str1 <- renderText({
paste(capture.output(str(input$Table1)), collapse = "\n")
})
output$str2 <- renderText({
paste(capture.output(str(input$Table1)), collapse = "\n")
})
}
I am not able to find out the input to be given for str()
Thanks
Balaji

Answer 1

Switch out your textOutput for verbatimTextOutput. Also, you require a reactive to treat the fileInput... specifically take note that you should trap the case when the input value is NULL.
app.R
library(shiny)
write.csv(mtcars, "mtcars.csv") # file created to test file input
ui <- fluidPage(
mainPanel(
verbatimTextOutput("strfile"),
fileInput("file1", "File")
)
)
server <- function(input, output) {
df <- reactive({
if (is.null(input$file1)) {
return(NULL)
} else {
read.csv(input$file1$datapath, row.names = 1) # note the row.names are dependent on your input requirements
}
})
output$strfile <- renderPrint({str(df())})
}
shinyApp(ui = ui, server = server)
To get this output...