[R] adding vertical segments to an xyplot in lattice

[Bert Gunter]

Well, a custom panel function is what you need (or one that may
already exist somewhere: try googling on "high low intervals in R
graphs" or some such).

So if you haven;t already done so, try Paul Morrell's Chapter on
lattice plots from his book for how panel functions work:

http://www.stat.auckland.ac.nz/~paul/RGraphics/chapter4.pdf

-- Bert


On Tue, Mar 22, 2011 at 12:12 PM, Christopher W Ryan
<cryan at binghamton.edu> wrote:
> I have a dataframe that looks like this:
>
>  > str(chr)
> 'data.frame':   84 obs. of  7 variables:
>  $ county: Factor w/ 3 levels "Broome","Nassau",..: 3 3 3 3 3 3 3 3 3 3 ...
>  $ item  : Factor w/ 28 levels "Access to healthy foods",..: 21 19 20
> 18 16 3 2 6 17 8 ...
>  $ value : num  8644 15 3.5 3.9 7.7 ...
>  $ low   : num  7897 9 2.5 2.6 7 ...
>  $ high  : num  9390 22 4.5 5.2 8.4 37 30 23 24 101 ...
>  $ target: num  5034 11 2.7 2.6 6.1 ...
>  $ nys   : num  6099 16 3.5 3.3 8 ...
>
>> head(chr)
>    county                      item  value    low   high target    nys
> 1 Sullivan           Premature death 8644.0 7897.0 9390.0 5034.0 6099.0
> 2 Sullivan       Poor or fair health   15.0    9.0   22.0   11.0   16.0
> 3 Sullivan Poor physical health days    3.5    2.5    4.5    2.7    3.5
> 4 Sullivan   Poor mental health days    3.9    2.6    5.2    2.6    3.3
> 5 Sullivan           Low birthweight    7.7    7.0    8.4    6.1    8.0
> 6 Sullivan             Adult smoking   29.0   22.0   37.0   15.0   20.0
>
> I'd like to graph high and low for "Premature death" for each of the
> three counties, with 3 vertical line segments, one connecting those
> two points for each county.  I can get the two points for each county:
>
>>xyplot(low+high ~ county, data=subset(chr, item=="Premature death"))
>
> but I have not yet been able to figure out how to draw the 3 vertical
> line segments. Been struggling to understand panel functions, but no
> success so far. I'd be grateful for any advice.
>
> Thanks.
>
> --Chris Ryan
> SUNY Upstate Medical University
> Clinical Campus at Binghamton
>
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-- 
Bert Gunter
Genentech Nonclinical Biostatistics