在knitr中，for循环中的pander没有输出

Question

在 RStudio 中使用 knitr，pander 在 for 循环中不会产生任何（或正确的）html 输出。这是一个最小的情况，作为 Rmd 输入文件。

---
title: "Untitled"
output: html_document
---

Testing why pander doesn't work in for loop

```{r global_options, include=FALSE}
knitr::opts_chunk$set(fig.width=7, fig.height=5, echo=FALSE, warning=FALSE,
  message=FALSE)

```

```{r}
library(pander)

r <- 1:10
print("pander at top level")   
pander(summary(r))    # works

print("pander in for loop")
for (i in 1:2) pander(summary(r))    #does not work (nothing in output)
for (i in 1:2) print(pander(summary(r)))    #does not work  (code in output)
for (i in 1:2) print(summary(r))    # works

```

其他（更有趣的）“摘要”对象的结果是相同的，例如lm适合的摘要。对于来自 CRAN 的 pander 0.5.2 以及从 github 加载的 0.5.3 也观察到了相同的行为。

RStudio v 0.99.467。

> sessionInfo()
R version 3.2.0 (2015-04-16)
Platform: x86_64-apple-darwin13.4.0 (64-bit)
Running under: OS X 10.10.4 (Yosemite)

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] pander_0.5.3

loaded via a namespace (and not attached):
 [1] minqa_1.2.4     MASS_7.3-40     Matrix_1.2-0    htmltools_0.2.6 tools_3.2.0    
 [6] yaml_2.1.13     Rcpp_0.11.6     rmarkdown_0.7   splines_3.2.0   nlme_3.1-120   
[11] grid_3.2.0      digest_0.6.8    nloptr_1.0.4    lme4_1.1-7      lattice_0.20-31

Answer 1

@daroczig 在 cmets 中回答：

1. 将 knitr 块选项 results 更改为 asis，在全局级别 knitr::opts_chunk$set(results="asis") 或在块级别 ```{r,results="asis"}
2. 禁用panderOption knitr.auto.asis : panderOptions('knitr.auto.asis', FALSE)

参照。 this issue

---
title: "Untitled"
output: html_document
---

Testing **when** pander doesn't work in for loop

```{r global_options, include=FALSE}
knitr::opts_chunk$set(fig.width=7, fig.height=5, echo=TRUE, warning=FALSE,
  message=FALSE)

```

```{r,results="asis"}
library(pander)
panderOptions('knitr.auto.asis', FALSE)

r <- 1:10

for (i in 1:2) pander(summary(r))

```