conditional plotting not working as expected in a shiny document

huangapple
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英文:

conditional plotting not working as expected in a shiny document

问题

我想制作闪亮文档，读者可以在不同版本的图表/表格之间进行选择。

第一个示例运行正常，但只有在选择选项二时，第二个示例才能运行。唯一的区别是if{}else{}与if{}if{}结构。

希望用户能够选择几个图表，而不仅仅是一个或两个。

英文:

I would like to make shiny documents in which the reader can choose between different versions of a graphs/table.

The first example works fine, but the second example only works if option two is selected. Only difference is if{}else{} vs if{}if{} structure.

would like for the user to choose a few graphs rather than just one or two.

  1. ---
  2. output: html_document
  3. runtime: shiny
  4. ---
  7. #```{r eruptions, echo=FALSE}
  8. inputPanel(
  9.   selectInput("option",
  10.     label = "Number of bins:",
  11.     choices = c(1, 2, 3), selected = 1
  12.   ),
  13. )
  15. renderUI({
  16.   if (input$option == 1) {
  17.     renderPlot({
  18.       plot(1:10)
  19.     })
  20.   } else {
  21.     renderPlot({
  22.       plot(1:10, 10:1)
  23.     })
  24.   }
  25. })
  26. #```
  28. #```{r eruptions2, echo=FALSE}
  29. inputPanel(
  30.   selectInput("option2",
  31.     label = "Number of bins:",
  32.     choices = c(1, 2, 3), selected = 1
  33.   ),
  34. )
  36. renderUI({
  37.   if (input$option2 == 1) {
  38.     renderPlot({
  39.       plot(1:10)
  40.     })
  41.   }
  42.   if (input$option2 == 2) {
  43.     renderPlot({
  44.       plot(1:10, 10:1)
  45.     })
  46.   }
  47. })
  50. </details>
  53. # 答案1
  54. **得分**: 1
  56. ```r
  57. R执行花括号内表达式的最后一条语句。如果 `input$option2 == 1`，它继续阅读代码，这是带有 `if(input$option == 2)` 的代码。由于这个条件未实现，输出为 `NULL`（不可见）。
  59. ```r
  60. &gt; x &lt;- if(2==3) {print(4)}
  61. &gt; x
  62. NULL

清楚吗？

  2. <details>
  3. <summary>英文:</summary>
  5. ```r
  6. renderUI({
  7.   if (input$option2 == 1) {
  8.     renderPlot({
  9.       plot(1:10)
  10.     })
  11.   }
  12.   if (input$option2 == 2) {
  13.     renderPlot({
  14.       plot(1:10, 10:1)
  15.     })
  16.   }
  17. })

R executes the last statement of the expression between the curly braces. If input$option2 == 1, it continues to read the code, the one with if(input$option == 2). Since this condition is not realized, the output is NULL (invisibly).

  1. &gt; x &lt;- if(2==3) {print(4)}
  2. &gt; x
  3. NULL

Is it clear?

huangapple
  • 本文由 发表于 2023年5月23日 00:04:47
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  • r
  • shiny
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