R - Shiny 的包裹 - 将情节发送到 Shiny

Question

我要构建一个网页，根据用户输入的簇数对鸢尾花数据进行聚类。它使用 K 均值算法对数据进行聚类并显示聚类数据图。它不起作用，我不知道为什么。我从这个链接开始: http://rstudio.github.io/shiny/tutorial/#sending-images

这是我的文件:ui.R

    library(shiny)

shinyUI(pageWithSidebar(
  headerPanel("Clustering iris Data"),
  sidebarPanel(
    sliderInput("k", "Number of clusters:",
                min = 1, max = 5,  value = 3)
  ),
  mainPanel(
    # Use imageOutput to place the image on the page
    imageOutput("myImage")
  )
))

和server.R

library(shiny)
library(caret)
library(ggplot2)
data(iris)

inTrain  <- createDataPartition(y=iris$Species, p=0.7, list=FALSE)
training <- iris[inTrain,]
testing  <- iris[-inTrain,]

shinyServer(function(input, output, session) {
  output$myImage <- renderImage({
    # A temp file to save the output.
    # This file will be removed later by renderImage
    outfile <- tempfile(fileext='.png')


    kMeans1 <- kmeans(subset(training,select=-c(Species)),centers=input$k)
    training$clusters <- as.factor(kMeans1$cluster)

    # Generate the PNG
    png(outfile, width=400, height=600)
    qplot(Petal.Width,Petal.Length,colour=clusters,data=training,main="iris Data Clusters")
    print(qplot)
    #plot(training$Petal.Width,training$Petal.Length,colour=clusters,data=training,main="iris Data Clusters")
    #hist(rnorm(input$k), main="Generated in renderImage()")
    #myImage

    dev.off()


    # Return a list containing the filename
    list(src = outfile,
         contentType = 'image/png',
         width = 400,
         height = 600,
         alt = "This is alternate text")
  }, deleteFile = TRUE)

})

Answer 1

我认为你只需要改变

qplot(Petal.Width,Petal.Length,colour=clusters,data=training,main="iris Data Clusters")
print(qplot)

像这样:

qP <- qplot(
      Petal.Width,Petal.Length,
      colour=clusters,data=training,
      main="iris Data Clusters")
    print(qP)

因为您对 qplot() 的调用实际上并未创建对象；这就是为什么 print(qplot) 在控制台打印 qplot 的函数定义。