Question

Usually when I plot some R line plot and set ylim=c(0,some_value), there is small space between the x axis and y=0.

I would like the y axis to show exactly at y=0 so points (x,0) will be plotted on the y axis (and not above).

Answer 1

You probably want the graphical parameters xaxs and yaxs with style “i”:

plot(1:10, rnorm(10), ylim=c(0,10), yaxs="i")

See ?par:

xaxs: The style of axis interval
calculation to be used for the x-axis.
Possible values are “r”, “i”, “e”,
“s”, “d”. The styles are generally
controlled by the range of data or
xlim, if given. Style “r” (regular)
first extends the data range by 4
percent at each end and then finds an
axis with pretty labels that fits
within the extended range. Style “i”
(internal) just finds an axis with
pretty labels that fits within the
original data range. Style “s”
(standard) finds an axis with pretty
labels within which the original data
range fits. Style “e” (extended) is
like style “s”, except that it is also
ensures that there is room for
plotting symbols within the bounding
box. Style “d” (direct) specifies that
the current axis should be used on
subsequent plots. (Only “r” and “i”
styles are currently implemented)

yaxs: The style of axis interval calculation to be used for the y-axis.
See xaxs above.