R闪亮错误:无法访问反应性消费者之外的反应性值“select_food”

Question

首先，我知道这个问题已经问过了，但答案帮不了我。

我的问题是:我正在编写一个小应用程序，根据几个输入绘制一个堆栈条形图。问题是输入2和3取决于第一个输入。

我正在使用粮农组织的数据集(你可以在这里找到它：http://www.fao.org/gleam/results/en/#top)，在这里你可以选择动物物种(牛、猪、鸡、.)然后，根据你选择的动物，你可以选择一种商品(肉类，乳制品，鸡蛋，.)和世界上的一个地区。下面是数据集的一个dput：

structure(list(Region = c("Global", "Global", "Global", "Global", 
"Global", "Global"), `Animal species` = c("Cattle", "Cattle", 
"Cattle", "Cattle", "Cattle", "Cattle"), `Production system` = c("Aggregated", 
"Aggregated", "Aggregated", "Grassland systems", "Grassland systems", 
"Grassland systems"), Commodity = c("Aggregated", "Milk", "Meat", 
"Aggregated", "Milk", "Meat"), `Emission intensity` = c(160.292607757249, 
86.7289320197207, 295.375059643258, 206.327939471892, 94.9887978082703, 
433.778095712786), Production = c(29163104087.7766, 18880885304, 
10282218783.7766, 10338174726.3435, 6940654475.5, 3397520250.84346
), `Total GHG emissions` = c(4674630004525.8, 1637519018002.76, 
3037110986523.04, 2133054289186.84, 659284424630.336, 1473769864556.5
), `Total CO2 emissions` = c(944929928440.176, 275691406265.277, 
669238522174.899, 562806229576.7, 92861399862.2565, 469944829714.444
), `Total CH4 emissions` = c(2648727469345.78, 967644226877.794, 
1681083242467.99, 1052965148816.85, 371346057784.129, 681619091032.719
), `Total N2O emissions` = c(1080972606739.85, 394183384859.689, 
686789221880.157, 517282910793.29, 195076966983.95, 322205943809.34
), `Feed, CO2` = c(353472898876.963, 138234019318.282, 215238879558.681, 
111398227143.195, 44040030065.8682, 67358197077.3266), `Feed, CH4` = c(0, 
0, 0, 0, 0, 0), `Feed: fertilizer & crop residues, N2O` = c(174073200018.734, 
71662075640.6952, 102411124378.039, 52536600648.293, 21561262083.5362, 
30975338564.7568), `Feed: applied & deposited manure, N2O` = c(741986436762.08, 
254388527100.44, 487597909661.64, 426761235035.348, 158783824942.446, 
267977410092.903), `LUC: soy & palm, CO2` = c(46879544227.8534, 
14974206675.1606, 31905337552.6928, 8194329546.5076, 2412100065.64785, 
5782229480.85975), `LUC: pasture expansion, CO2` = c(387006214285.714, 
0, 387006214285.714, 387006214285.714, 0, 387006214285.714), 
    `Enteric fermentation, CH4` = c(2509275304012.47, 885635162795.57, 
    1623640141216.9, 996909632562.869, 336901779434.28, 660007853128.589
    ), `Manure management, CH4` = c(139452165333.309, 82009064082.2245, 
    57443101251.0844, 56055516253.9789, 34444278349.8494, 21611237904.1294
    ), `Manure management, N2O` = c(164912969959.032, 68132782118.5531, 
    96780187840.4786, 37985075109.6489, 14731879957.9685, 23253195151.6804
    ), `Direct energy, CO2` = c(42155419009.351, 29934851370.7, 
    12220567638.651, 14173264181.2837, 10786045291.1, 3387218890.18368
    ), `Indirect energy, CO2` = c(15856531895.5915, 3252888569.33446, 
    12603643326.2571, 4303271766.469, 999843540.840469, 3303428225.62853
    ), `Postfarm, CO2` = c(99559320144.7024, 89295440331.8, 10263879812.9024, 
    37730922653.5311, 34623380898.8, 3107541754.7311)), row.names = c(NA, 
-6L), class = c("tbl_df", "tbl", "data.frame"))

当我只使用三个selectInput运行我的代码时，它都能工作，但是当我试图运行这个情节时，不幸的是，它不再起作用了。我总是会犯错误：

错误:无法访问反应性使用者之外的反应性值“select_food”。

这是我的密码：

body <- dashboardBody(
  
  useShinyjs(),
  
  #tags$head(tags$style(HTML('.small-box .icon-large {top: 5px;}'))),
  
  tabItems(
    ################################### AGRI ###########################
    tabItem("agri",
            fluidRow(
              
              box(title="GHG emissions per food product - Livestock w/ FAO Database",status="success",solidHeader = FALSE, collapsible = TRUE, 
                                                                                                                uiOutput("select_food"),
                  uiOutput("secondSelection"),
                  uiOutput("region"),
                  plotlyOutput("ghg_food"),
                  width = 12)
            )       
    )
  )
 
)

ui <- dashboardPage(header, sidebar, body, skin = skin)

对于服务器部分：

server <- function(input, output) {
  
  output$select_food <- renderUI({
    selectInput("select_food", "Choose a product", 
                choices = unique(gleam$`Animal species`), 
                multiple = FALSE,
                selected = "Cattle")
    
  })

  output$secondSelection <- renderUI({
    if (!is.null(input$select_food)){
      data_input <- reactive({input$select_food})
      selectInput("commodity", "Choose a commodity", choices = as.character(unique(gleam[gleam$`Animal species` == data_input(),]$Commodity)), multiple = FALSE, selected = "Meat")
    }
  })
  
  output$region <- renderUI({
    if (!is.null(input$select_food) & !is.null(input$commodity)){
      data_input2 <- reactive({input$commodity})
      data_input <- reactive({input$select_food})
      selectInput("region", "Choose one or several regions", choices = as.character(unique(gleam[(gleam$`Animal species` == data_input()) & (gleam$Commodity == data_input2()),]$Region)), multiple = TRUE, selected = "Global")
    }
  })
  

  output$ghg_food <- plotlyOutput({
    
    if (!is.null(input$select_food)){
     data_input <- reactive({input$select_food})
     data_input_food <- data_input()
    }
    if (!is.null(input$commodity)){
      data_input2 <- reactive({input$commodity})
      data_input2_commo <- data_input2
    }
    if (!is.null(input$region)){
      data_input3 <- reactive({input$region})
      data_input3_reg <- data_input3()
    }
    
    chosen_animal <- data_input_food
    chosen_commodity <- data_input2_commo
    chosen_reg <- data_input3_reg

    animal_commo <- gleam %>%
      filter(`Animal species` == chosen_animal, Commodity == chosen_commodity, Region %in% chosen_reg)

    decomp <- animal_commo %>%
      select(-c('Emission intensity', 'Production', 'Total GHG emissions', 'Total CO2 emissions', 'Total CH4 emissions', 'Total N2O emissions', 'Animal species', 'Production system', 'Commodity'))

    df_decomp <- melt(decomp, id.var="Region")

    ggplotly(
      ggplot(df_decomp, aes(x = reorder(Region, value, sum), y = value, fill = variable)) +
        geom_bar(stat = "identity") +
        theme_minimal() +
        ylab("") +
        xlab("") +
        labs(fill='Emissions from ') +
        ggtitle("GHG emissions per kg of food product") +
        scale_fill_brewer(palette="RdYlBu") +
        coord_flip() +
        theme(panel.grid.major = element_blank(), panel.grid.minor = element_blank(), legend.position="bottom") ,
      tooltip = c("x", "fill")
    )

  })
  
}

shinyApp(ui = ui, server = server)

我不明白反应性的需要，也不明白为什么我的代码不能工作。

Answer 1

您的错误主要是因为在定义plotlyOutput时使用了renderPlotly而不是renderPlotly。您可以通过在renderUI之外定义数据来简化它。虽然有些步骤是多余的，因为用例可能不一样，但我仍然保留了流。尝尝这个

server <- function(input, output, session) {
  
  output$selectfood <- renderUI({
    selectInput("select_food", "Choose a product", 
                choices = unique(gleam$`Animal species`), 
                multiple = FALSE,
                selected = "Cattle")
    
  })
  
  data_input <- reactive({
    req(input$select_food)
    input$select_food
  })

  output$secondSelection <- renderUI({
    req(input$select_food)
    if (!is.null(input$select_food)){

      selectInput("commodity", "Choose a commodity", choices = as.character(unique(gleam[gleam$`Animal species` == input$select_food,]$Commodity)), multiple = FALSE, selected = "Meat")
    }
  })

  data_input2 <- reactive({
    req(input$commodity)
    input$commodity
  })
  
  output$region <- renderUI({
    if (!is.null(input$select_food) & !is.null(input$commodity)){

      #data_input <- reactive({input$select_food})
      selectInput("region", "Choose one or several regions", choices = as.character(unique(gleam[(gleam$`Animal species` == data_input()) & (gleam$Commodity == data_input2()),]$Region)), multiple = TRUE, selected = "Global")
    }
  })

  data_input3 <- reactive({
    req(input$region)
    input$region
  })
  
  df_decomp <- reactive({
    req(data_input(),data_input2(),data_input3())
    if (!is.null(input$select_food)){
      #data_input <- reactive({input$select_food})
      data_input_food <- data_input()
    }
    if (!is.null(input$commodity)){
      #data_input2 <- reactive({input$commodity})
      data_input2_commo <- data_input2()
    }
    if (!is.null(input$region)){
      #data_input3 <- reactive({input$region})
      data_input3_reg <- data_input3()
    }
    
    chosen_animal <- data_input_food
    chosen_commodity <- data_input2_commo
    chosen_reg <- data_input3_reg
    
    animal_commo <- gleam %>%
      filter(`Animal species` == chosen_animal, Commodity == chosen_commodity, Region %in% chosen_reg)
    
    decomp <- animal_commo %>%
      select(-c('Emission intensity', 'Production', 'Total GHG emissions', 'Total CO2 emissions', 'Total CH4 emissions', 'Total N2O emissions', 'Animal species', 'Production system', 'Commodity'))
    
    df <- melt(decomp, id.var="Region")
    df
  })
  
  
  output$ghg_food <- renderPlotly({
    req(df_decomp())
    
    ggplotly(
      ggplot(df_decomp(), aes(x = reorder(Region, value, sum), y = value, fill = variable)) +
        geom_bar(stat = "identity") +
        theme_minimal() +
        ylab("") +
        xlab("") +
        labs(fill='Emissions from ') +
        ggtitle("GHG emissions per kg of food product") +
        scale_fill_brewer(palette="RdYlBu") +
        coord_flip() +
        theme(panel.grid.major = element_blank(), panel.grid.minor = element_blank(), legend.position="bottom"),
      tooltip = c("x", "fill")
    )
    
  })
  
}

shinyApp(ui = ui, server = server)

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