The x and y labels for maps
tm_xlab(text, size, color, rotation, space, fontface, fontfamily, alpha, side)tm_ylab(text, size, color, rotation, space, fontface, fontfamily, alpha, side)
text of the title
font size of the title
color
rotation in degrees
space between label and map in number of line heights
font face
font family
alpha transparency of the text
side: "top"
or "bottom"
for tm_xlab
and "left"
or "right"
for tm_ylab