[R] Bar Plot with Connected Points on 1 Y-Axis

[jimdare]

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
> 
> ______________________________________________
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> and provide commented, minimal, self-contained, reproducible code.
> 
> 

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