hook_movecode()
is a document hook to move code chunks out of LaTeX
floating environments like figure and table when the chunks
were actually written inside the floats. This function is primarily designed
for LyX: we often insert code chunks into floats to generate figures or
tables, but in the final output we do not want the code to float with the
environments, so we use regular expressions to find out the floating
environments, extract the code chunks and move them out. To disable this
behavior, use a comment % knitr_do_not_move
in the floating
environment.