geom_gene_arrow() draws genes as arrows, allowing gene maps to be drawn.
As standard for ggplot2.
grid::unit() object giving the width of the
arrowhead. Defaults to 4 mm. If the gene is drawn smaller than this width,
only the arrowhead will be drawn, compressed to the length of the gene.
grid::unit() object giving the height of the
arrowhead. Defaults to 4 mm.
grid::unit() object giving the height of the body
of the arrow. Defaults to 3 mm.
This geom draws genes as arrows along a horizontal line representing the
molecule. The start and end locations of the gene are expressed with the
xmax aesthetics, while the molecule can be specified with the
y aesthetic. Optionally, an additional
forward aesthetic can be used to
reverse the orientation of some or all genes from that implied by
Unless the plot is faceted with a free x scale, all the molecules will share
a common x axis. This means that if the locations are very different across
different molecules, the genes might appear very small and squished together
with a lot of unnecessary empty space. To get around this, either facet the
scales = "free_x", or normalise the gene locations if their
exact locations are not important.
make_alignment_dummies() for a method to align genes between molecules.
xmin,xmax (start and end of the gene; will be used to determine gene orientation)
forward (if any value that is not TRUE, or coercible to TRUE, the gene
arrow will be drawn in the opposite direction to that determined by