B Lab 1: Light (More Details)

B.1 The chem_table function

The chem_table function is essentially a wrapper function to the pandoc.table function in the pander package. Here is the code for chem_table:

chem_table <- function(data, caption){
  names(data) <- pandoc.strong.return(names(data))
  pandoc.table(data, caption = caption, style = "multiline",
               split.tables = Inf)
  cat("\\newline")
}

We see here that chem_table expects two arguments:

• data is a data frame containing the variables you’d like to appear in the table
• caption is the caption we’d like to correspond to this table

Remember that you can run ?chemistr::chem_table to bring up the help documentation for the function.

We first use the pandoc.strong.return function that bolds the column names. We then call the pandoc.table function in the pander package with data as our argument and then our entered caption parameter as the caption argument to pandoc.table. The last two argument for style and split.tables are used to ensure the outputted table appears as you might expect it to in the Word document:

• style set to multiline allow headers and table rows to span multiple lines of text. This may be helpful if you have long column names.

• split.tables set to Inf ensures that wide tables will not be split into multiple tables.

Lastly, the cat("\\newline") code specifies that an extra line of white space will be printed immediately following the table.

B.2 The include_graphics function

The include_graphics function enables you to include pictures that are stored as image files (*.png or *.jpg, for example) into your Word document via R Markdown. It is a function in the knitr package. If you’d like more information on how to use include_graphics run ?knitr::include_graphics in the R Console. The important argument here is path which tells R where to look for the file you want to include.

If you include your pictures in the same directory as your Rmd file you need only specify the name of the file here in quotation marks. If you have a figure folder in the same folder as your R Markdown file, you’ll need to specify that via something like:

knitr::include_graphics("figure/myimage.png")

Whatever you specify as the chunk option fig.cap will appear as the figure caption. You are also encouraged to name the R chunk, which will allow you to reference the figure later in your document as well as automatic numbering of the figures:

```{r myimage, echo=FALSE, fig.cap="Here is my picture"}

knitr::include_graphics("figure/myimage.png")

```

We could then reference our picture in the text of our document by using \@ref(fig:myimage).