Simple Shiny Code with argument missing

Question

I'm just starting out on Shiny and have been working with a dataset to try and get some experience. I've reworked a simple code for quite a few iterations and keep getting the ...argument is missing with no default. Does anyone see what I'm missing?

ui.R
=============================
library(shiny)

shinyUI(
  pageWithSidebar(

    headerPanel("Simple Cluster Example"),

    sidebarPanel(   
      numericInput("var", "Cluster:", 2,
                   min = 2, max = 5, step = 1)),

    mainPanel(
      plotOutput("plot"),  
      #dataTableOutput("table")
    )
  )
)
-------------------------------

server.R
===============
library('shiny')
library('ggplot2')
shinyServer(function(input, output) {  


  protein <- read.csv("protein.csv")
  vars.to.use <- colnames(protein) [-1]
  pmatrix <- scale(protein[,vars.to.use])
  pcenter <- attr(pmatrix, "scaled:center")
  pscale <- attr(pmatrix, "scaled:scale")
  d <- dist(pmatrix, method="euclidean")
  pfit <- hclust(d, method="ward.D")

  # This code is triggered whenever the drop-down menu is changed in the UI
  component <- input$var
  #rect.hclust(pfit, k=component)
  groups <- cutree(pfit, k=component)
  princ <- prcomp(pmatrix)
  nComp <- 2
  project <- predict(princ, newdata=pmatrix) [,1:nComp]
  project.plus <- cbind(as.data.frame(project),
                        cluster=as.factor(groups),
                        country=protein$Country)
  p <- ggplot(project.plus, aes(x=PC1, y=PC2)) +
    geom_point(aes(shape=cluster))+geom_text(aes(label=country), hjust=0, vjust=1)

  output$plot <- renderPlot({print(p)})


})

Answer 1

Your problem is:

plotOutput("plot"),  

When you end with "," (since you commented out the line after) it expects a new argument. But it is empty in your case, so remove the extra ",".