R devel - May 2008 - A small modification of plot.acf (patch)

In one of my scripts I used plot.acf function, but I had to modify it
a little to suit my needs. Although my modifications are minor, I
believe some people might benefit from it.

The problem: currently, in cross-correlation plots main title captions
are constructed of 2 names separated by '&' symbol. Such captions
occupy too much horizontal space and usually don't fit in plot. A
better solution would be to split a caption in two lines (each name on
its separate line).

I attach a patch which adds an option to do so. Please review it and
tell me if such things are worth including into upstream version. I
have never contributed code for R project before, so please be patient
and tell me if I'm missing some fundamental things (like compatibility
with S or whatever).

The patch attached does 2 things:

1) Adds new argument main.sep. It allows to customize the titles. Now
you can even pass main.sep value containing '\n', so two parts of the
caption come on different lines. The default value preserves original
behavior.

2) Changes main title captions positioning behavior. Now they are
positioned automatically, which ensures nicely looking captions when
main.sep containing '\n' is used.

If you think the patch might be useful, please let me know and I will
submit necessary modifications to the Rd file.

Andrey Paramonov
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On Sun, 25 May 2008, ?????? ????????? wrote:
> In one of my scripts I used plot.acf function, but I had to modify it
> a little to suit my needs. Although my modifications are minor, I
> believe some people might benefit from it.
>
> The problem: currently, in cross-correlation plots main title captions
> are constructed of 2 names separated by '&' symbol. Such
captions
> occupy too much horizontal space and usually don't fit in plot. A
> better solution would be to split a caption in two lines (each name on
> its separate line).
That is the part that needs justification.  I've never seen an example 
where that was the case (and you don't give one), and I use acf() a lot. 
The examples fit and their series names are not particularly short.

Also, the user has the option to supply 'main' to plot.acf via
'...', so
why is that not sufficient?  And you can even suppress the title by 
main="" and use title() for even more control.

> I attach a patch which adds an option to do so. Please review it and
> tell me if such things are worth including into upstream version. I
> have never contributed code for R project before, so please be patient
> and tell me if I'm missing some fundamental things (like compatibility
> with S or whatever).
>
> The patch attached does 2 things:
>
> 1) Adds new argument main.sep. It allows to customize the titles. Now
> you can even pass main.sep value containing '\n', so two parts of
the
> caption come on different lines. The default value preserves original
> behavior.
>
> 2) Changes main title captions positioning behavior. Now they are
> positioned automatically, which ensures nicely looking captions when
> main.sep containing '\n' is used.
>
> If you think the patch might be useful, please let me know and I will
> submit necessary modifications to the Rd file.
>
> Andrey Paramonov
>
-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

2008/5/27 Prof Brian Ripley <ripley at
stats.ox.ac.uk>:
> That is the part that needs justification.  I've never seen an example
where
> that was the case (and you don't give one), and I use acf() a lot. The
> examples fit and their series names are not particularly short.
>
> Also, the user has the option to supply 'main' to plot.acf via
'...', so why
> is that not sufficient?  And you can even suppress the title by
main="" and
> use title() for even more control.
>
Here is an example with real-life series names and plot dimensions:

data <- cbind('????? ???????'  = arima.sim(n = 100, list(ar = 0.5)),
             '???. ?????????' = arima.sim(n = 100, list(ar = 0.1)))

x11(width = 4.8, height = 4.2)
acf(data, mar = c(3, 3, 3, 1) + 0.1, cex.main = 1)

I have tried to supply main argument to the acf function:

acf(data, mar = c(3, 3, 3, 1) + 0.1, cex.main = 1,
   main = matrix(c('????? ???????',
     '????? ??????? &\n???. ?????????',
     '????? ??????? &\n???. ?????????',
     '???. ?????????'), 2, 2))

but it doesn't work the desired way. Please see the implementation of
plot.acf. title function doesn't seem to play well with par(mfrow = ),
so it doesn't help, too.

In principle, it's not *that* hard to implement a custom version of
multivariate acf plot, but the current version of plot.acf provides
some sweet features like y-axes alignment etc. Writing another
plot.acf will inevitably lead to massive code duplication, which is
bad.

I have several ideas of how to tweak current plot.acf so it would
suffice my needs:

1) Add new main.sep argument (see the patch).

2) Let plot.acf recognize if main is a matrix and use its elements for
different plots, not just coerce it to vector and pass to every title.

3) Let plot.acf recognize if main is a function and call it with 2
arguments (i-series name and j-series name) to compose captions.

1) seems to be the easiest for a user, 2) and 3) provide more freedom.

Andrey Paramonov