如何在向量中存储文本输入，以便稍后与R shiny一起使用？

Question

我希望将两个变量(“ticker”和"SharesVec")定义为空向量，并在触发按钮“操作”时向这些向量添加文本输入和数字输入(分别)。稍后我将使用这些向量来运行一个函数。我不确定我是否理解如何在R shiny (初学者)中正确使用变量。这是我到目前为止尝试过的：

用户界面

shinyUI(fluidPage(
    
    titlePanel("Portfolio Analysis Tool"),
    br(),
    
    sidebarLayout(
        sidebarPanel(
            selectInput(
                inputId =  "DateFrom", 
                label = "Starting Year (YYYY-01-01)", 
                choices = format(Sys.Date(), "%Y"):1975    
            ),
            selectInput(
                inputId =  "DateTo", 
                label = "Ending Year (YYYY-12-31)", 
                choices = format(Sys.Date(), "%Y"):1975    
            ),
            h2("Initial Portfolio"),
            p("Include every ticker owned at some point during the period (Number of shares = 0 if none are held at the starting date)", style = "font-size: 12px"),
            textInput("Stock","Ticker"),
            numericInput("Shares","Number of Shares",0, min = 0, step = 0.5),
            column(12,
                  splitLayout(cellWidths = c("58%", "58%"),
                        actionButton("action", "Add",icon("dollar-sign"),  
                            style="color: #fff; background-color: #337ab7; border-color: #2e6da4"),
                        actionButton("action1", "Reset",icon("trash"),  
                            style="color: #fff; background-color: #337ab7; border-color: #2e6da4"))),
            br(),
            br(),
            h2("Rebalancing"),
            dateInput("DateReb", "Date of Purchase/Sale"),
            textInput("Stock1", "Ticker"),
            numericInput("Shares1","Number of Shares (+/-)", 0, step = 0.5),
            column(12,
                   splitLayout(cellWidths = c("58%", "58%"),
                               actionButton("action2", "Add",icon("dollar-sign"),  
                                            style="color: #fff; background-color: #337ab7; border-color: #2e6da4"),
                               actionButton("action3", "Reset",icon("trash"),  
                                            style="color: #fff; background-color: #337ab7; border-color: #2e6da4"))),
            br(),
            br(),
        ),
        
        mainPanel(
            column(10,
                   splitLayout(cellWidths = c("50%", "50%"),
                               htmlOutput("InitialHoldings", style = "font-weight: bold; text-decoration: underline"),
                               htmlOutput("Rebalancing", style = "font-weight: bold; text-decoration: underline"))),
            br(),
            br(),
            column(12,
                tableOutput("table"), 
                style = "height:340px; overflow-y: scroll; border: 1px solid #e3e3e3; border-radius: 8px; background-color: #f7f7f7;text-align: left"),
            textOutput("TEST")
       )
    )
))

服务器

library(quantmod)                            
library(PerformanceAnalytics)

tickers <- c()
SharesVec <- c()

shinyServer(function(input, output) {
    
  output$InitialHoldings <- renderText({paste("Initial Holdings")})
  output$Rebalancing <- renderText({paste("Rebalancing")})

  #Store Initial Stocks/Nb of Shares from User Inputs
  values <- reactiveValues()
  values$df <- data.frame("Stock" = numeric(0), "Shares" = numeric(0))
  newEntry <- observe({
    if(input$action > 0) {
      isolate(values$df[nrow(values$df) + 1,] <- c(input$Stock, input$Shares))
      tickers <- c(tickers,input$Stock)
      SharesVec <- c(SharesVec,input$Shares)
    }
  })
  output$table <- renderTable({values$df})
  output$TEST <- renderText({paste(tickers)})

})

注意:我已经在代码中包含了output$TEST，以查看向量“ticker”是否正确地自我更新。另外，我想指出的是，由于我添加了行

tickers <- c(tickers,input$Stock)
SharesVec <- c(SharesVec,input$Shares)

在服务器中，操作按钮不能正常工作(不再需要它来向我的表中添加数据)。我也尝试过使用全局变量->>，但似乎不起作用。有人能帮帮我吗？

Answer 1

将向量存储在reactiveValues中。您可以将服务器函数更改为：

library(shiny)

shinyServer(function(input, output) {
  
  output$InitialHoldings <- renderText({paste("Initial Holdings")})
  output$Rebalancing <- renderText({paste("Rebalancing")})
  
  #Store Initial Stocks/Nb of Shares from User Inputs
  values <- reactiveValues(tickers = NULL, SharesVec = NULL)
  
  observeEvent(input$action, {
    values$tickers <- c(values$tickers,input$Stock)
    values$SharesVec <- c(values$SharesVec,input$Shares)
  })
    
  output$TEST <- renderText({
       paste(values$tickers, values$SharesVec, sep = ':', collapse = '\n')
  })
  
}

使用output$TEST向您显示存储的值。