brad-cannell / r4epi

Repository for the R for Epidemiology book
http://www.r4epi.com/
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Improve explanation of comments #135

Open mbcann01 opened 3 months ago

mbcann01 commented 3 months ago

Add distinction between comments and headers to the end of chapter 7.  Call it 7.7 Things to keep in mind when using R Markdown files. Or something like that. Refer back to 4.6.

2020-06-03 a student asked this question at the bottom of the lab:

"I’m still a bit confused on the difference between the this text and the #comment from the line above. I understand that the explanatory text can be formatted etc. in markdown, but is there any reason to use #comments in these files (or just in R scripts?) **After exporting to html, I now am assuming that the ## are headers"

Here was my answer, which I can probably use in the book:

Comments (as a concept) can be written in markdown documents or in R scripts. As you correctly pointed out, the syntax for writing comments (how to write them) differs depending on where you write them.

In R scripts: R scripts only allow comments that begin with #. Additionally, comments in R scripts can't really be formatted or styled.

In R Markdown files (including Notebooks): Comments can be written plain text anywhere in the Notebook file except inside a code chunk. Inside a code chunk, comments must still begin with #. Remember, code chunks are kind of like little individual R scripts.

In R Markdown files (including Notebooks): Comments can be formatted and styled using markdown syntax. In markdown syntax # represents a level-1 header, ## represents a level-2 header, ### represents a level-3 header and #### represents a level-4 header.

In R Markdown files (including Notebooks): When would you choose to write comments around code chunks with markdown vs. writing comments inside code chunks with #? This is a good question and I'm not aware of any specific guidelines on this. I tend to write about 95% of my comments using markdown because of the ability to format and style it. However, I do sometimes still write comments inside code chunks. I think I typically do this to explain how a specific piece of code in the chunk works rather than what the chunk is trying to do overall.