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首页 > 解决方案 > 如何使用 for 循环和 ifs 从数据框中返回值以匹配闪亮服务器中的输入值

shiny - 如何使用 for 循环和 ifs 从数据框中返回值以匹配闪亮服务器中的输入值

问题描述

我已经为闪亮的应用程序设置了 ui 和服务器。我还有一个数据框我的一组变量。我正在尝试使用 if 语句循环遍历行数据框，以将我选择的输入与数据框中的列相匹配。然后返回最后一列中的值（结果/分数）。

我为这篇文章重新创建了一个更小的简化版本的代码和数据集。

我尝试使用过滤器来过滤掉数据框中的条件并返回我想要的值。我也尝试过单独使用 if 语句，但无济于事。

我的数据集的列和行数比下面创建的要多，但为简单起见：

 z <-  c("Perfect", "Edible", "Spoiled", "Perfect", "Edible",  "Spoiled", "Perfect", "Edible", "Spoiled", "Perfect", "Edible", "Spoiled", "Perfect", "Edible", "Spoiled", "Perfect", "Edible", "Spoiled", "Perfect", "Edible", "Spoiled", "Perfect", "Edible", "Spoiled")

 y <-  c("Fruit", "Fruit", "Fruit","Vegetable", "Vegetable", "Vegetable", "Fruit", "Fruit", "Fruit","Vegetable", "Vegetable", "Vegetable", "Fruit", "Fruit", "Fruit","Vegetable", "Vegetable", "Vegetable", "Fruit", "Fruit", "Fruit","Vegetable", "Vegetable", "Vegetable")

x <-  c("A", "A","A","A","A","A", "B", "B", "B", "B", "B", "B", "C", "C","C","C","C","C", "D", "D","D","D","D","D")

result  <- runif(24, 50, 500)

用户界面：

    library("shiny")    
    shinyUI(
    pageWithSidebar(
    headerPanel("Demo")
    ,
    sidebarPanel(
    wellPanel(
    selectInput(
         inputId= 'x', 
         label= "Country of Origin", 
         choices= list('A', 'B', 'C', 'D'),
         selected='A',
         multiple= FALSE),

    selectInput(
          inputId= 'y', 
          label= "Product",
          choices= list("Fruit", "Vegetable"),
          selected='Fruit',
          multiple= FALSE),

    selectInput(
          inputId= 'z',
          label= "Quality",
          choices = list("Perfect", "Edible", "Spoiled"),
          multiple= FALSE)

  )
)
,
mainPanel(
    wellPanel(
          textOutput("score")))))

服务器.R：

  shinyServer(
  function(input,output,session){

   score <- reactive({
     for (row in 1:nrow(df())) {
     if(input$x == df$x[row] && input$y == df$y[row] && input$z == df$z){
   score$result <- df$result[row] 
       }
      }
     })

output$score <- renderText({
score$result})  
   })

我希望相应的结果分数会显示在应用程序的主面板中，该面板会根据所选输入进行更新。目前我发现我根本没有得到任何输出。

任何帮助将不胜感激。

标签： shinyshinydashboardshiny-servershiny-reactivityshinyapps

解决方案

我不确定，但您是否尝试执行以下操作（请参见下面的代码）。在这种情况下，您不需要 for 循环。

library("shiny")
library("dplyr")

z <-  c("Perfect", "Edible", "Spoiled", "Perfect", "Edible",  "Spoiled", "Perfect", "Edible", "Spoiled", "Perfect", "Edible", "Spoiled", "Perfect", "Edible", "Spoiled", "Perfect", "Edible", "Spoiled", "Perfect", "Edible", "Spoiled", "Perfect", "Edible", "Spoiled")

y <-  c("Fruit", "Fruit", "Fruit","Vegetable", "Vegetable", "Vegetable", "Fruit", "Fruit", "Fruit","Vegetable", "Vegetable", "Vegetable", "Fruit", "Fruit", "Fruit","Vegetable", "Vegetable", "Vegetable", "Fruit", "Fruit", "Fruit","Vegetable", "Vegetable", "Vegetable")

x <-  c("A", "A","A","A","A","A", "B", "B", "B", "B", "B", "B", "C", "C","C","C","C","C", "D", "D","D","D","D","D")

df = data.frame(x, y, z, result = runif(24, 50, 500), stringsAsFactors = FALSE)

shinyApp(

    ui =  shinyUI(
        pageWithSidebar(
            headerPanel("Demo")
            ,
            sidebarPanel(
                wellPanel(
                    selectInput(
                        inputId= 'x', 
                        label= "Country of Origin", 
                        choices= list('A', 'B', 'C', 'D'),
                        selected='A',
                        multiple= FALSE),

                    selectInput(
                        inputId= 'y', 
                        label= "Product",
                        choices= list("Fruit", "Vegetable"),
                        selected='Fruit',
                        multiple= FALSE),

                    selectInput(
                        inputId= 'z',
                        label= "Quality",
                        choices = list("Perfect", "Edible", "Spoiled"),
                        multiple= FALSE)

                )
            )
            ,
            mainPanel(
                wellPanel(
                    textOutput("score"))))),

    # Server ------
    server = function(input, output, session){

                score <- reactive({

                    df %>% 
                        filter(x == input$x,
                               y == input$y,
                               z == input$z)

                })

                output$score <- renderText({

                    score()$result

                    })

    }        
) # Closes ShinyApp

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