在 Reshape2 dcast() 中使用来自 Shiny 的多个输入答案

【问题标题】：Using an multiple input from Shiny in Reshape2 dcast()在 Reshape2 dcast() 中使用来自 Shiny 的多个输入
【发布时间】：2018-11-03 14:23:29
【问题描述】：

参考Using an input from Shiny Widget in Reshape Cast(), 我可以通过单行变量的 Shiny 输入创建动态汇总表。

但是，当我希望创建多个行层列时，我发现找不到第二个或第三个对象。我试图打印出公式，这似乎是正确的。比如Shiny中选择了“vs”和“hp”，那么公式就变成了“vs + hp~gear”，看起来是对的。但是会出现“object 'hp' not found”的错误。

您能帮我解决这个问题吗？谢谢！

用户界面：

library(shiny)
library(dplyr)
library(reshape2)
library(DT)

ui <- fluidPage(
  headerPanel("Summary Table"),
  sidebarPanel(selectInput("row", "Row variable", names(mtcars), selected = "vs", multiple = T),
               selectInput("col", "Column variable", names(mtcars), selected = "gear")),
  mainPanel(DT::dataTableOutput('table'))
)

服务器：

server <- function(input, output) {

  output$table <- renderDataTable({

    formula <- as.formula(paste(paste(input$row, collapse = "+"), "~", input$col))
    print(formula)

    car0 <- mtcars %>% 
      group_by_(input$row, input$col) %>% 
      summarize(n = n_distinct(cyl)) %>% 
      dcast(formula, value.var = "n")   

    datatable(car0)

  })
}

shinyApp(ui, server)

【问题讨论】：

标签： r shiny reshape2 dcast

【解决方案1】：

像这样？

library(shiny)
library(dplyr)
library(reshape2)
library(tidyr)
library(DT)
ui <- fluidPage(
  headerPanel("Summary Table"),
  sidebarPanel(selectInput("row", "Row variable", names(mtcars), selected = "vs", multiple = T),
               selectInput("col", "Column variable", names(mtcars), selected = "gear")),
  mainPanel(DT::dataTableOutput('table'))
)

server <- function(input, output) {

  output$table <- renderDataTable({

    car0 <- mtcars %>% 
      select(input$row,input$col,cyl)%>%
      group_by_at(., vars(input$row, input$col))%>%
      summarize(n = n_distinct(cyl))%>%
      tidyr::spread(input$col,n)


    datatable(car0)

  })
}

shinyApp(ui, server)

对于公式和reshape2

library(shiny)
library(dplyr)
library(reshape2)
library(tidyr)
library(DT)
ui <- fluidPage(
  headerPanel("Summary Table"),
  sidebarPanel(selectInput("row", "Row variable", names(mtcars), selected = "vs", multiple = T),
               selectInput("col", "Column variable", names(mtcars), selected = "gear")),
  mainPanel(DT::dataTableOutput('table'))
)

server <- function(input, output) {

  output$table <- renderDataTable({

    formula <- as.formula(paste(paste(input$row, collapse = "+"), "~", input$col))
    print(formula)

    car0 <- mtcars %>% 
      select(input$row,input$col,cyl)%>%
      group_by_at(., vars(input$row, input$col))%>%
      summarize(n = n_distinct(cyl))%>%
      #tidyr::spread(input$col,n)
      dcast(formula, value.var = "n")  


    datatable(car0)

  })
}

shinyApp(ui, server)

【讨论】：

谢谢，这确实解决了我的问题。但仍然想知道如何使用公式函数来实现这一点。