如何在Rmarkdown演示文稿（滑动式）中回显代码之前显示块输出？

杰森·弗里斯（Jason Freels）

我最近开始在Rmarkdown中使用Slidy演示模板，并且喜欢每个幻灯片如何允许您向下滚动以获取更多内容。

我使用此方法的一种方法是与学生共享地块（请参见下面的示例代码）。在单张幻灯片上，我可以显示该图以及用于创建该图的确切代码，可以向下滚动查看该代码。

---
title: Echo Code Chunks After Code Results
subtitle: Thanks For Your Help
author: Me
date: "today"
output: slidy_presentation
runtime: shiny
---

## Slide with Interactive Plot

```{r, echo=TRUE, warning=FALSE, message=FALSE}
shinyApp(options = list(width = "100%", height = "700px"),
  ui = ( fluidPage(
inputPanel(
  selectInput("n_breaks", label = h3("Number of bins:"),
              choices = c(10, 20, 35, 50), selected = 20),

  sliderInput("bw_adjust", label = h3("Bandwidth:"),
              min = 0.2, max = 2, value = 1, step = 0.2)),
    plotOutput("stuff", height = "650px")

)),

server = function(input,output,session) {

  output$stuff = renderPlot({
  hist(faithful$eruptions, probability = TRUE, 
breaks = as.numeric(input$n_breaks),
xlab = "Duration (minutes)", main = "Geyser eruption duration", 
col = "bisque", border = 1)

  dens <- density(faithful$eruptions, adjust = input$bw_adjust, lwd = 2, col = "blue")
  lines(dens, col = "blue")
})
})
```

我遇到的问题是，默认行为是在代码生成之前回显代码块，这与我想要的方式相反。

我显然可以通过插入两个代码块来解决此问题，其中第一个具有块选项echo=FALSE，第二个具有块选项，echo=TRUE, fig.show='hide'但这需要我确保两个代码块都匹配。如何在回显代码之前颠倒此顺序以使绘图显示。

与往常一样，感谢您的帮助。

A5C1D2H2I1M1N2O1R2T1

您应该可以使用以下内容来完成演示文稿的内容。

## Slide with Interactive Plot

```{r thecode, echo=FALSE, warning=FALSE, message=FALSE}
shinyApp(options = list(width = "100%", height = "700px"),
  ui = (fluidPage(inputPanel(
    selectInput("n_breaks", label = h3("Number of bins:"), 
                choices = c(10, 20, 35, 50), selected = 20),
    sliderInput("bw_adjust", label = h3("Bandwidth:"), 
                min = 0.2, max = 2, value = 1, step = 0.2)),
    plotOutput("stuff", height = "650px"))),

server = function(input,output,session) {
  output$stuff = renderPlot({
    hist(faithful$eruptions, probability = TRUE, 
         breaks = as.numeric(input$n_breaks), xlab = "Duration (minutes)", 
         main = "Geyser eruption duration", col = "bisque", border = 1)
    dens <- density(faithful$eruptions, adjust = input$bw_adjust, 
                    lwd = 2, col = "blue")
    lines(dens, col = "blue")})
  })
```

```{r thecode, eval=FALSE}
```

那是：