Define knitr options for an R Markdown output format that creates HTML output.
knitr_options_html(fig_width, fig_height, fig_retina, keep_md,
dev = "png")Default width (in inches) for figures
Default height (in inches) for figures
Scaling to perform for retina displays (defaults to 2, which
currently works for all widely used retina displays). Set to NULL to
prevent retina scaling. Note that this will always be NULL when
keep_md is specified (this is because fig_retina relies on
outputting HTML directly into the markdown document).
Keep the markdown file generated by knitting.
Graphics device to use for figure output (defaults to png)
An list that can be passed as the knitr argument of the
output_format function.