You can generalize the approach by using something like:
...
ylim = c(0, max(DF$TACC, DF$Catch) * 1.1)
...
That would allow you to use the max value of the two columns, multiplied
by a fudge factor, which you can adjust as needed. In this case,
increasing the y axis range by 10% to make room.
HTH,
Marc
on 01/07/2009 02:31 PM jimdare wrote:
Thanks Marc, that has helped a lot. Say, for example, in a situation
where I
can't find out the highest value, is there any way to get R to
automatically
detect this and adjust the axis accordingly? I am planning to do this
for
many different stocks at once and dont wan't to have to define the
highest
value for each. I could set a standard axis value based on the max
values
of all stocks, however the detail will be lost for many of the less
exploited species.
Marc Schwartz wrote:
on 01/06/2009 09:07 PM jimdare wrote:
Hi Everyone,
Have created a bar plot of the data below using the following code:
barplot(TACC,space=0,names.arg=Year). I now want to add a series of
connected points to represent the catch. I tried to do this using
line(Catch) or points(Catch), however both of these commands result in
each
data point being aligned with the right edge of each bar. I need them
to
be
solid points in the centre of each bar, and for each point to be
connected
to its neighbour by a line. Another issue I have is when the points
exceed
the values for the bar graph (e.g. in 2004 and 2005 catch>TACC) R seems
to
cut them off, I need the axis to be expanded so they can be seen. I'm
sure
these are relatively simple problems but I am really stuck. Thanks
very
much for all your help, it is much appreciated.
James
DATA:
Year Species Stock TACC Catch
1 2001 ORH OR1 5000 4687
2 2002 ORH OR1 6000 3215
3 2003 ORH OR1 7000 6782
4 2004 ORH OR1 9000 10000
5 2005 ORH OR1 9000 12000
One key point to note is that barplot() returns the bar midpoints. This
is noted in the help for barplot(). The bars are not centered on integer
axis values, so you need the returned values to place additional
annotation in the proper location relative to the bars.
The other thing is to set the range of the y axis using the maximum
value in Catch, plus some fudge, so that the plot covers both sets of
data and has enough room for the additional points.
Thus, presuming that your data is in a data frame called 'DF':
mp <- barplot(DF$TACC, space = 0, names.arg = DF$Year,
ylim = c(0, 13000))
# Now use lines() to add Catch
lines(mp, DF$Catch, type = "b", pch = 19)
See ?barplot, ?lines and ?points for more information.
HTH,
Marc Schwartz