使用 knitr 有条件地绘制多个 d3heatmaps

Question

当尝试在条件内绘制多个 d3heatmaps 时，生成的 HTML 仅绘制最终热图。下面是用于重现错误的 RMD 代码。

---
title: "test"
output: html_document
---

This is an R Markdown document. 

```{r}
require(d3heatmap)
myVar = TRUE
if (myVar == TRUE) {
  d3heatmap(mtcars, col = "Spectral")
  d3heatmap(mtcars, col = "Blues")
}
```

如果热图不符合条件，编织的 HTML 文件中将出现多个。还有其他人运行参与其中吗？

sessionInfo()
R version 3.2.3 (2015-12-10)
Platform: x86_64-apple-darwin13.4.0 (64-bit)
Running under: OS X 10.11.3 (El Capitan)

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] d3heatmap_0.6.1.1

loaded via a namespace (and not attached):
 [1] htmlwidgets_0.6 magrittr_1.5    htmltools_0.3   tools_3.2.3     base64enc_0.1-3
 [6] yaml_2.1.13     stringi_1.0-1   rmarkdown_0.9.5 knitr_1.12.3    stringr_1.0.0  
[11] digest_0.6.9    evaluate_0.8.3  png_0.1-7

Answer 1

中解释了根本问题：HTML 个小部件 "only work when they are generated from top-level R expressions"。这解释了为什么将绘图包装在 if 语句中不起作用。尽管如此，第二个图还是可见的，因为 if returns 计算的最后一个表达式的值，因此 "raising" 最后一个图到顶层。

作为解决方案，可以将绘图收集在列表中并按照建议通过 htmltools::tagList 打印 :

```{r}
require(d3heatmap)
myVar = TRUE
res <- list()
if (myVar == TRUE) {
  res[[1]] <- d3heatmap(mtcars, col = "Spectral")
  res[[2]] <- d3heatmap(mtcars, col = "Blues")
}

htmltools::tagList(res)
```

使用 knitr 有条件地绘制多个 d3heatmaps

Issue plotting multiple d3heatmaps in conditional with knitr

r

knitr

r-markdown

d3heatmap