Graph is not displayed in shiny [R] - r

Question

I am using shiny package in R to take input from user and plot the X and Y variable against each other as line plot.There is no error displayed.Everything is displayed except for the graph.Please can someone help why the graph is not displayed .Here is the ui.r file
library(shiny) # load the shiny package
setwd("C:/indiahacks2")
dat<-read.csv("final.csv")
# Define UI for application
shinyUI(fluidPage(
# Header or title Panel
titlePanel(h4('Impulse Response on VAR MODEL', align = "center")),
# Sidebar panel
sidebarPanel(
selectInput("Impulse", label = "1. Select the Impulse Variable",
choices = names(dat)),
selectInput("Response", label = "1. Select the Response Variable",
choices = names(dat)),
sliderInput("Lag", "2. Select the number of histogram BINs by using the slider below", min=0, max=25, value=10),
radioButtons("colour", label = "3. Select the color of histogram",
choices = c("Green", "Red",
"Yellow"), selected = "Green")
),
# Main Panel
mainPanel(
textOutput("text1"),
textOutput("text2"),
textOutput("text3"),
textOutput("text3"),
plotOutput("myhist")
)
)
)
Server.r
library(shiny) # Load shiny package
dat<-read.csv("final.csv")
shinyServer(
function(input, output) {
output$text1 <- renderText({
colm = as.numeric(input$Impulse)
paste("Impulse Variable is", names(dat[colm]))
})
output$text2 <- renderText({
paste("Color of plot is", input$radio)
})
output$text3 <- renderText({
paste("Number of Lags is", input$Lag)
})
output$text4 <- renderText({
colm = as.numeric(input$Response)
paste("Response Variable is", names(dat[colm]))
})
output$myhist <- renderPlot(
{
colm = as.numeric(input$Impulse)
colm1 = as.numeric(input$Response)
plot(dat[,colm],dat[,colm1])})
})

Answer 1

So there a couple of things wrong with your script, upon further inspection:
1) colm cannot be referenced by output$text4. This is because of scoping...
2) When you comment-out the output$text4 code I now receive an undefined column error in the plot call. This is because forcing your column choices to numeric returns NA.
Below should do what you are looking for.
Here is the server.R code:
library(shiny) # Load shiny package
dat<-read.csv("final.csv")
shinyServer(
function(input, output) {
output$text1 <- renderText({
colm = as.numeric(input$Impulse)
paste("Impulse Variable is", columns()[2])
})
output$text2 <- renderText({
paste("Color of plot is", input$radio)
})
output$text3 <- renderText({
paste("Number of Lags is", input$Lag)
})
output$text4 <- renderText({
colm = as.numeric(input$Response)
paste("Response Variable is", columns()[2])
})
columns<-reactive({
colm = as.character(input$Impulse)
colm1 = as.character(input$Response)
return(c(colm, colm1) )
})
output$myhist <- renderPlot(
{
plot(dat[,columns()[1]],dat[,columns()[2]],type="b")})
})
*Ui.R
# Define UI for application
library(shiny)
shinyUI(fluidPage(
# Header or title Panel
titlePanel(h4('Impulse Response on VAR MODEL', align = "center")),
# Sidebar panel
sidebarPanel(
selectInput("Impulse", label = "1. Select the Impulse Variable",
choices = names(dat)),
selectInput("Response", label = "1. Select the Response Variable",
choices = names(dat)),
sliderInput("Lag", "2. Select the number of histogram BINs by using the slider below", min=0, max=25, value=10),
radioButtons("colour", label = "3. Select the color of histogram",
choices = c("Green", "Red",
"Yellow"), selected = "Green")
),
# Main Panel
mainPanel(
textOutput("text1"),
textOutput("text2"),
textOutput("text3"),
textOutput("text4"),
plotOutput("myhist")
)
)