Question

With following chunk the left alignment doesn’t work. The resulting map has still the same left border as without fig.align='left'

\documentclass[a4paper, oneside, british]{book}
\begin{document}
<<chunk.maps, fig.height=12, fig.width=21, out.width="6in", fig.align='left'>>=
library(knitr)
library(maptools)
data(wrld_simpl)
plot(wrld_simpl)
box()
@
\end{document}

I would greatly appreciate any help with this!

Thanks,
Gerit

Answer 1

It is not because fig.align="left" does not work; as @joran said in the comments, it does work if you make the plot smaller. There are two problems that caused the artifact:

1. par(mar) is not 0 on the left margin by default; see ?par; set par(mar = c(0, 0, 0, 0)) solves this problem
2. the plot was written into a paragraph, which has an amount of indentation by default in LaTeX (\parindent)

To make the plot touch the left margin, try this:

\documentclass{book}
\setlength{\parindent}{0pt}
\begin{document}
<<chunk.maps, fig.height=12, fig.width=21, out.width="6in", fig.align='left'>>=
library(maptools)
data(wrld_simpl)
par(mar = c(0, 0, 0, 0))
plot(wrld_simpl)
box()
@
\end{document}

If you are uncomfortable with setting \parindent to 0, you can restore it after the chunk.