【发布时间】：2020-10-01 11:41:11
【问题描述】：
我遇到了以下问题。为了使用 Rexams 自动生成问题集，我想从数据库中读取问题，然后将它们解析为 Rexams 模板，然后生成另一个降价文件，该文件可能包含 R 代码块，然后应该由 Rexams 处理。我尝试了几种获取逐字文本的形式，例如
write_chunk1 <- c("```{r, echo = FALSE, results='hide'} \n " )
write_chunk2 <- c(" include_supplement('UCL-J16-Q13-01.png', recursive = TRUE) \n" )
write_chunk3 <- c("```")
cat(noquote(write_chunk1) )
cat(noquote(write_chunk2) )
cat(noquote(write_chunk3) )
但这不会在生成的降价文件中产生所需的输出。如下（我逃脱了最后一个代码关闭，否则它也不会显示在这里）
```{r, echo = FALSE, results='hide'}
include_supplement('UCL-J16-Q13-01.png', recursive = TRUE)
```
以下文件运行一个循环，将“测验”数据库放入 Rexams 模板中
library(knitr)
library(rmarkdown)
library(here)
library(exams)
library(dplyr)
library(readxl)
## paths
# file.copy(here("quizzes/input/images","*.png"),to = here("quizzes/output/rmd_question_files/"))
## Data
quizzes <- tribble(
~identifier, ~question, ~answer1, ~answer2, ~solution1, ~solution2, ~feedback1, ~feedback2, ~image,
"Q1", "Is this good", "yes", "no", 1, 0, "Because it is", "Wrong", "smile.png"
)
## Loop
for (i in 1:nrow(quizzes)){
rmarkdown::render(input = here("quizzes/code/", "template_rexams.Rmd"),
output_format = "md_document",
output_file = paste0(quizzes$Identifier[i], ".Rmd"),
output_dir = here("quizzes/output/rmd_question_files/")
)
}
rexams 模板用作应该包含不同练习的降价文件的模板。
---
output: md_document
---
```{r echo=FALSE, message=FALSE, warning=FALSE}
quizzes <- tribble(
~question, ~answer1, ~answer2, ~solution1, ~solution2, ~feedback1, ~feedback2, ~image,
"Is this good", "yes", "no", 1, 0, "Because it is", "Wrong", "smile.png"
)
# Read question
question <- quizzes$question[i]
# Create answer lists and solutions with feeback
answers <- c(quizzes$answer1[i], quizzes$answer2[i])
sol <- c(quizzes$solution1[i], quizzes$solution2[i])
sol <- ifelse(sol == 1, TRUE, FALSE)
feedback <- c(quizzes$feedback1[i], quizzes$feedback2[i])
## Get image identifiers
img1 <- quizzes$image
```
```{r get-images, echo=FALSE, message=FALSE, warning=FALSE}
# Define variable containing image locations
img_path <- here::here("quizzes/input/images/")
img1_pt <- ifelse(img1 != "", paste0(img_path, paste0(quizzes$image[i],".png")), "")
img1 <- ifelse(img1 != "", paste0(quizzes$image,".png"), "")
if (!is.na(img1)){
include_supplement(file = c(img1), dir = img_path, recursive = TRUE)
}
write_chunk1 <- c("{r, echo = FALSE, results='hide'} \n " )
write_chunk2 <- c(" include_supplement('")
write_chunk3 <- c(paste0(img1, ", recursive = TRUE) \n" ))
write_chunk4 <- c("```")
```
```{r write_supplement, echo=FALSE, message=FALSE, warning=FALSE, results="asis"}
cat(noquote(write_chunk1) )
cat(noquote(write_chunk2), noquote(write_chunk3) )
cat(noquote(write_chunk4) )
```
Question
========
**Unit `r unit`.`r nmb`**
`r question`
```{r insert-images, echo=FALSE, message=FALSE, warning=FALSE, comment="", results="asis"}
img1_pr <- ifelse(img1 != "", paste0("![](", paste0(img1, ")")), " ")
```
`r if(!is.na(img1)){noquote(img1_pr)}`
```{r answerlist, echo = FALSE, results = "asis"}
answerlist(answers, markup = "markdown")
```
Solution
========
```{r solutionlist, echo = FALSE, results = "asis"}
answerlist(ifelse(sol == 1, "**True**", "**False**"), markup = "markdown", feedback)
```
Meta-information
================
extype: mchoice
exsolution: `r mchoice2string(sol, single = FALSE)`
exname: `r exname`
现在的问题是，这个新的 markdown 文件应该在 markdown 文件的开头包含以下代码块，其中要包含的图像的名称会随着练习而改变。
```{r, echo = FALSE, results='hide'}
include_supplement('smile.png', recursive = TRUE)
```
我希望这能更好地解释我的问题。我认为我的问题是我不知道如何转义 ``` 以便将其写入文件。
【问题讨论】：
-
很难理解，尤其是我不知道 Rexams 模板的外观等。您能否尝试添加一个带有一个问题的完整可重现示例。
-
谢谢，我发布了更多关于我正在使用的较短版本代码的问题的详细信息。
-
我认为使用
writeLines()而不是cat()会是更简单的解决方案吗？此外，您可能有兴趣查看 R-Forge 论坛上的讨论：r-forge.r-project.org/forum/… 也许您可以尝试使该策略适应您的数据格式？如果您仍然遇到问题或有疑问，请修改您的问题，我会尝试看看。 -
谢谢，
writeLines并删除块选项results="asis"并添加comments=NA成功了，现在一切都在write_supplement块中正确转义，现在从数据库自动生成考试包括补充作品。
标签： r-markdown markdown knitr r-exams