6.6 LaTeX sub-figures
Sometimes you may want to include multiple images in a single figure environment. Sub-figures allow us to achieve this by arranging multiple images within a single environment and providing each with its own sub-caption.
Sub-figures require the LaTeX package subfig. We can load it via the
extra_dependencies YAML option within the
pdf_document output. For example:
To arrange all plots from a code chunk in sub-figures, you have to use the chunk options
fig.cap (the caption for the whole figure environment) and
fig.subcap (a character vector of the captions for sub-figures). For best output, you can also use the following options:
fig.ncol: The number of columns of sub-figures. By default, all plots are arranged in a single row. You can break them into multiple rows.
out.width: The output width of individual plots. You will normally set this to
100%divided by the number of columns. For example, if you have two plots, the
out.widthoption should be equal to or less than
50%, otherwise the plots may exceed the page margin.
Below is an illustrative example:
The output is shown in Figure 6.2. For the sake of simplicity, we omitted a few chunk options in the chunk header of the above example, including
fig.ncol = 2,
out.width = "50%",
fig.align = "center", and the actual long captions.