[R] How to add a common title (or xlab, ylab) for multi-plots in the same window?

[Martin Maechler]

>>>>> "Sundar" == Sundar Dorai-Raj <sundar.dorai-raj at pdf.com>
>>>>>     on Mon, 02 Aug 2004 12:53:43 -0500 writes:

    Sundar> F Duan wrote:

    >> I am using par(mfrow=c()) to plot multi-figures in the
    >> same window. And I like to put a common title (and xlab,
    >> ylab) for all of plots. I have already left some margin
    >> by resetting omi values in par() and hided all (xlab,
    >> ylab) for each sub-plot. Could anyone tell me how to do that?

    >> Thanks a lot,
    >> 
    >> Frank

   Sundar> ?mtext allows this if outer = TRUE.

and others have mentioned the same.
I'm not answering the "(or xlab, ylab)" part in the original
question, something which *is* answered by ``use mtext(..)''.

Because it such a common task to want an overall title for
"multi-plots", and furthermore, because in many typical
situations, the default "spacing" {par("mar") etc} around the
individual plots is too large (i.e. the plots get smaller than
necessary with their white space margins using too much of your
device's real estate), I had written a small utility function,
mult.fig(), many years ago {in 1990! for S-plus}, and made it
available in the 'sfsmisc' package for a while now.

The start of its help page is :

>> mult.fig               package:sfsmisc               R Documentation
>> 
>> Plot Setup for MULTiple FIGures, incl. Main Title
>> 
>> Description:
>> 
>>      Easy Setup for plotting multiple figures (in a rectangular layout)
>>      on one page.  It allows to specify a main title and uses _smart_
>>      defaults for several 'par' calls.

a typical use after
     install.packages("sfsmisc")
     library(sfsmisc)

is simply

     mult.fig(<#{plots}>, main = <overall title>)

such as the one in example(mult.fig)  :

     mult.fig(5, main= expression("Sine Functions " * sin(n * pi * x)))
     x <- seq(0, 1, len = 201)
     for (n in 1:5)
       plot(x, sin(n * pi * x), ylab ="", main = paste("n = ",n))
     par(old.par)

[BTW: The function has one really ugly feature (that I've unfortunately
      not eliminated long time ago and now it would break too
      much code): It defines the *GLOBAL* variable  'old.par'
      as seen in the above example.
 Good programming practice would use the return value of
 mult.fig()  (which *does* contain old.par!)
 Yuck! - what a bad programming style I was using 14 years ago....
]
      
Martin Maechler