分配动态变量以重塑 idvar

Question

我的数据框：

structure(list(NEWSEC = c("A1", "A1", "A1", "A1", "A2", "A2", 
"A2"), tiles = structure(c(1L, 2L, 3L, 4L, 1L, 2L, 3L), .Label = c("1st", 
"2nd", "3rd", "4th"), class = c("ordered", "factor")), AVG = c(360, 
594, 868, 1534, 349, 592, 861)), .Names = c("NEWSEC", "tiles", 
"AVG"), row.names = c(NA, 7L), class = "data.frame")

看起来像这样：

  NEWSEC tiles  AVG
1     A1   1st  360
2     A1   2nd  594
3     A1   3rd  868
4     A1   4th 1534
5     A2   1st  349
6     A2   2nd  592
7     A2   3rd  861

当我使用 base R 的 reshape 函数时

reshape(df, idvar = "NEWSEC", timevar = "tiles", direction = "wide")

这非常有效...但我的数据框是通过闪亮的应用程序输入动态生成的，我可以 select 市场或类别而不是 NEWSEC。通常我将输入变量分配给一个对象并在我的函数中引用该对象。示例：

sec <- input$colvar

但是，当我尝试类似的重塑方法时，它不起作用。到目前为止我的代码：

reshape(df, idvar = sec, timevar = "tiles", direction = "wide").

我也试过用引号粘贴变量 sec 但没有成功。

reshape(df, idvar = paste(""",sec,""", sep = "), timevar = "tiles", direction = "wide").

我不知道这是否正确...但刚刚试过了。

Answer 1

这部分代码是正确的

sec <- input$colvar
reshape(df, idvar = sec, timevar = "tiles", direction = "wide")

前提是您在反应上下文（reactive/render* 函数）中执行此操作，并且前提是 df 已经有这两个新列。

但是，您将这两个变量动态添加到数据框 df，因此您必须在某些 reactive/eventReactive 函数中执行此操作，例如：

data <- reactive({
    # let's pretend that this only happens when some conditions are met
    new <- df
    new$Market <- gl(n = 2, k = 4, length = 7, labels = c("Market1", "Market2"))
    new$Category <- gl(n = 2, k = 4, length = 7, labels = c("Cat1", "Cat2"))
    new
  })

比如说，现在您想根据所选的 id 变量重塑这个新的动态数据框，然后将其呈现为 table。为此，您必须使用 renderTable 函数并通过 data().

访问您的新数据框

output$new <- renderTable({
    # access dynamic data frame "data" via "data()"
    sec <- input$colvar 
    reshape(data(), idvar = sec, timevar = "tiles", direction = "wide")
  })

完整示例：

library(shiny)

df <- structure(list(NEWSEC = c("A1", "A1", "A1", "A1", "A2", "A2", 
                          "A2"), tiles = structure(c(1L, 2L, 3L, 4L, 1L, 2L, 3L),
                          .Label = c("1st", "2nd", "3rd", "4th"),
                          class = c("ordered", "factor")), 
                          AVG = c(360,594, 868, 1534, 349, 592, 861)), 
                          .Names = c("NEWSEC", "tiles", "AVG"), 
                          row.names = c(NA, 7L), class = "data.frame")

ui <- fluidPage(
  fluidRow(
    column(4, 
           selectInput("colvar", "Variable:", 
                        choices = c("NEWSEC", "Market", "Category"))
    ),
    column(8, 
           h4("old"), tableOutput("old")
    ),
    h4("new"), tableOutput("new"))
)


server <- function(input, output) {

  # dynamic data frame 
  data <- reactive({
    new <- df
    new$Market <- gl(n = 2, k = 4, length = 7, labels = c("Market1", "Market2"))
    new$Category <- gl(n = 2, k = 4, length = 7, labels = c("Cat1", "Cat2"))
    new
  })

  output$old <- renderTable({
    # access dynamic data frame "data" via "data()"
    data()
  })

  output$new <- renderTable({
    # access dynamic data frame "data" via "data()"
    sec <- input$colvar 
    reshape(data(), idvar = sec, timevar = "tiles", direction = "wide")
  })
}

shinyApp(ui = ui, server = server)

分配动态变量以重塑 idvar

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