r - 是否可以从 Shiny 的应用程序创建用户定义的报告？

Question

下面这个 Shiny 的应用程序是从图库中取出的。它允许用户选择变量、构建线性回归并下载报告。

如果我事先不知道用户想要构建多少个绘图和模型并将其包含到报告中怎么办？是否可以创建包含动态添加图的报告？

服务器.R

function(input, output) {

    regFormula <- reactive({
        as.formula(paste('mpg ~', input$x))
    })

    output$regPlot <- renderPlot({
        par(mar = c(4, 4, .1, .1))
        plot(regFormula(), data = mtcars, pch = 19)
    })

    output$downloadReport <- downloadHandler(
        filename = function() {
            paste('my-report', sep = '.', switch(
                input$format, PDF = 'pdf', HTML = 'html', Word = 'docx'
            ))
        },

        content = function(file) {
            src <- normalizePath('report.Rmd')

            # temporarily switch to the temp dir, in case you do not have write
            # permission to the current working directory
            owd <- setwd(tempdir())
            on.exit(setwd(owd))
            file.copy(src, 'report.Rmd', overwrite = TRUE)

            library(rmarkdown)
            out <- render('report.Rmd', switch(
                input$format,
                PDF = pdf_document(), HTML = html_document(), Word = word_document()
            ))
            file.rename(out, file)
        }
    )

}

ui.R

fluidPage(
    title = 'Download a PDF report',
    sidebarLayout(
        sidebarPanel(
            helpText(),
            selectInput('x', 'Build a regression model of mpg against:',
                        choices = names(mtcars)[-1]),
            radioButtons('format', 'Document format', c('PDF', 'HTML', 'Word'),
                         inline = TRUE),
            downloadButton('downloadReport')
        ),
        mainPanel(
            plotOutput('regPlot')
        )
    )
)

报告.Rmd

Here is my regression model:

```{r model, collapse=TRUE}
options(digits = 4)
fit <- lm(regFormula(), data = mtcars)
b   <- coef(fit)
summary(fit)
```

The fitting result is $mpg = `r b[1]` + `r b[2]``r input$x`$.
Below is a scatter plot with the regression line.

```{r plot, fig.height=5}
par(mar = c(4, 4, 1, 1))
plot(regFormula(), data = mtcars, pch = 19, col = 'gray')
abline(fit, col = 'red', lwd = 2)
```

Answer 1

嗯，看来我找到了答案。问题出在局部/全局变量中。我必须将列表初始化放在服务器功能之外。我还必须使用 <<-而不是<-将新元素分配给绘图而不是每次都创建新绘图。

非常感谢 Peter Ellis 的支持!

所以，解决方案是(我稍微更改了初始代码以专注于重要部分):

服务器.R

library(ggplot2); library(shiny); library(grid); library(gridExtra)


plist <- list() # IMPORTANT - outside server function

shinyServer(function(input, output) {

    output$regPlot <- renderPlot({
        p <- do.call("grid.arrange", c(plotList(),
                                       ncol=floor(sqrt(length(plotList())+1)),
                                       top = "test"))
    })



    plotList <- eventReactive(input$plt2rprt, {
        p <- ggplot(data = mtcars, aes_string(x = input$x, y = "mpg")) +
            geom_point()
 #       isolate(
        plist[[length(plist)+1]] <<- p #IMPORTATNT <<- instead of <-
 #       )
        return(plist)
    })


    output$lengthOfList <- renderText({length(plotList())})
    output$lll <- renderText({length(plist)})

    output$downloadReport <- downloadHandler(
        filename = function() {
            paste('my-report', sep = '.', switch(
                input$format, PDF = 'pdf', HTML = 'html', Word = 'docx'
            ))
        },

        content = function(file) {
            src <- normalizePath('report.Rmd')

            owd <- setwd(tempdir())
            on.exit(setwd(owd))
            file.copy(src, 'report.Rmd', overwrite = TRUE)

            library(rmarkdown)
            out <- render('report.Rmd', switch(
                input$format,
                PDF = pdf_document(), HTML = html_document(), Word = word_document()
            ))
            file.rename(out, file)
        }
    )

}) #ShinyServer

ui.R

fluidPage(
    title = 'Download a PDF report',
    sidebarLayout(
        sidebarPanel(
            helpText(),
            selectInput('x', 'Build a regression model of mpg against:',
                        choices = names(mtcars)[-1]),
            actionButton("plt2rprt", label = "Include into report"),
            hr(),
            radioButtons('format', 'Document format', c('PDF', 'HTML', 'Word'),
                         inline = TRUE),
            downloadButton('downloadReport')
        ),
        mainPanel(
            plotOutput('regPlot'),
            #verbatimTextOutput("count"),
            hr(),
            textOutput("lengthOfList"),
            textOutput("lll"),
            helpText("test-test-test")
        )
    )
)

报告.Rmd

Length of list of plots `r length(plotList())`

```{r plot, fig.height=5}
do.call("grid.arrange", c(plotList(),
                          ncol=floor(sqrt(length(plotList())+1)),
                          top = "test"))
```