What is the command in RMarkdown to “source” and display the code from an existing .R file?

Question

Example: My R script is named \"code.R\". It produces a simple plot of y versus x. And looks like this in Rmarkdown.

    ````{r eval=FALSE}
    ## code in \"         


        

Answer 1

Solution found on: http://yihui.name/knitr/demo/externalization/

Start your input.R script with the comment "## ---- input.R" (without the quotes)

Make an .Rmd script with the following code and Knit it. It will show the content of the input.R script in the resulting PDF.

      ---
      output: pdf_document
      ---

      ```{r cache=FALSE, echo=FALSE}
      knitr::read_chunk('input.R')
      ```

      ```{r input.R, eval=FALSE}

      ```