CODEWITHSUNDEEP
rknitr
Oskar Gauffin
Oskar Gauffin

Reputation: 35

Second evaluation of inline R code in knitr

I'm trying to create a math test generator which randomizes which questions that are included in a test. I imagine writing 20 questions or so in knitr, and then pressing a button to create a pdf with a subset of them. I'm using R Markdown in Rstudio. I imagine a solution somewhat like: 

```{r}
start<-"";end<-""

if(0<runif(1)){
start1<-"```{r, echo=F}" 
end1<-"```"
}
```

`r start1`
Question 1
`r end1`

But this results in a pdf with:

```{r, echo=F}
Question 1
```

How do I tell knitr to evaluate the inline code a second time? Or is there a slicker way of doing things?

Upvotes: 3

Views: 184

Answers (1)

Rentrop
Rentrop

Reputation: 21507

You can use cat for that:

---
title: "Math test"
---

```{r Setup-Chunk, echo=FALSE}
q1 <- "Note down the Pythagorean theorem?"
q2 <- "Sum of angles of a triangle?"
q3 <- "What is the root of $x^2$?"
questions <- c(q1,q2,q3)
selection <- sample(length(questions), 2) # by altering 2 you pick the number of questions
```

```{r, results='asis', echo=FALSE}
out <- c()
for(i in selection){
  out <- c(out, questions[i])
}
cat(paste("###", seq_along(selection), out,collapse = "  \n"))
```

Visual:
enter image description here

Upvotes: 1

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