From ripley@stats.ox.ac.uk  Fri Jun 21 18:18:38 2002
From: ripley@stats.ox.ac.uk (ripley@stats.ox.ac.uk)
Date: Fri, 21 Jun 2002 18:18:38 +0100 (BST)
Subject: The title function does not always work properly when used to
 add a global title to a figure containing several plots.
In-Reply-To: <200206211654.SAA14292@luc.ac.be>
Message-ID: <Pine.LNX.4.31.0206211809200.2626-100000@gannet.stats>

Try

par(mfrow=c(2,2),oma=c(0,0,4,0))
plot(1:3,1:3,xlab="",ylab="",main="")
title(main="This should be the title of this figure.", outer=TRUE)

which is how it is intended that this be done.

All your examples work (as I expect from S) for me that way.

Basically, after par(mfrow=c(1,1),oma=c(0,0,0,0)) you have no outer
margin nor do you have a plot region set yet (and the next call which
does would clear the screen).  So your call to title() should probably
fail as in

> title(main="This should be the title of this figure.")
Error in title(main = "This should be the title of this figure.") :
        plot.new has not been called yet

It would be desirable if it either gave an error message or worked.

On Fri, 21 Jun 2002, Patrick Lindsey wrote:

> Hi everyone,
>   The following problem occurs with R-1.5.1 on an Intel laptop running
> RedHat 7.2, with R-1.5.0 on an Alpha server running OSF 4.0 and on a
> SGI server running IRIX 6.5, and with version of R as old as 1.2.3 (I
> only tried older version under RedHat 7.2 and R-1.2.3 is the oldest I
> still currently have installed). The complete of these three different
> platforms can be found at the end of my email.
>   The problem is the following. I am trying to add a global title to a
> figure which contains several plots. Although I am not convince the
> method I am using (see below) is the best way to achieve this, I
> noticed that it failed to add the title in certain cases but not in
> others. I included below some examples where it works and where it
> does not work for me. As the same behavior occurs on all three
> platforms I have access to, I guess that everyone (perhaps not does on
> MS-Windows or on a Mac) should be able to see the problem by running
> my code (if this is not the case, please let me know and I shall
> provide some postscript files illustrating the problem).
>   Unfortunately, the c-code to print text to the graphic window is
> very complex and I am not familiar with it. As I thought that the
> problem was related with the "title" function, I started by looking at
> the "do_title" subroutine (R_HOME/src/main/plot.c). From there, I went
> to the "GText" subroutine (R_HOME/src/main/graphics.c) which appears
> to call the subroutine "clipText" to print the text to the canvas (but
> I could already be wrong about this...). But in any case, I was not
> able to trace down the problem as each of these subroutines appears to
> get entered as expected with parameters containing the expected values
> but then "clipText" appears to call ((GEDevDesc*) dd)->dev->text(...)
> which I longer understand... On the other hand, I no longer think that
> the problem is actually coming from the "title" function but rather
> from a global variable (or perhaps a "par" option) that is not always
> reset (or initialized) properly... by at least functions such as
> "title" and plot.default with options "axis", "ylab", "xlab", or
> "main" when the option "mfrow" is not set to "c(1,1)" in the "par"
> options.
>   I hope that this is understandable... but in any case, the following
> examples should clarify things up.
>
> # OK
> par(mfrow=c(2,2),oma=c(0,0,4,0))
> plot(1:3,1:3,xlab="",ylab="",main="")
> par(mfrow=c(1,1),oma=c(0,0,0,0))
> title(main="This should be the title of this figure.")
>
> # Not OK (global title not at all printed)
> par(mfrow=c(2,2),oma=c(0,0,4,0))
> plot(1:3,1:3,xlab="This is the x-axis label.",ylab="",main="")
> par(mfrow=c(1,1),oma=c(0,0,0,0))
> title(main="This should be the title of this figure.")
>
> # Not OK (global title not at all printed)
> par(mfrow=c(2,2),oma=c(0,0,4,0))
> plot(1:3,1:3,xlab="",ylab="This is the y-axis label.",main="")
> par(mfrow=c(1,1),oma=c(0,0,0,0))
> title(main="This should be the title of this figure.")
>
> # Not OK (global title not at all printed)
> par(mfrow=c(2,2),oma=c(0,0,4,0))
> plot(1:3,1:3,xlab="This is the x-axis label.",
>      ylab="This is the y-axis label.",main="")
> par(mfrow=c(1,1),oma=c(0,0,0,0))
> title(main="This should be the title of this figure.")
>
> # Not OK (global title not at all printed)
> par(mfrow=c(2,2),oma=c(0,0,4,0))
> plot(1:3,1:3,xlab="This is the x-axis label.",
>      ylab="This is the y-axis label.",main="a)")
> par(mfrow=c(1,1),oma=c(0,0,0,0))
> title(main="This should be the title of this figure.")
>
> # OK
> par(mfrow=c(2,2),oma=c(0,0,4,0))
> plot(1:3,1:3,xlab="This is the x-axis label.",
>      ylab="This is the y-axis label.",main="a)",axes=F)
> axis(1)
> axis(2)
> box()
> par(mfrow=c(1,1),oma=c(0,0,0,0))
> title(main="This should be the title of this figure.")
>
> # Strange... but can perhaps help in identifying the problem.
> par(mfrow=c(2,2),oma=c(0,0,4,0))
> plot(1:3,1:3,xlab="This is the x-axis label.",
>      ylab="This is the y-axis label.",main="a)")
> par(mfrow=c(1,1),oma=c(0,0,0,0))
> title(main="This should be the title of this figure.")
> title(main="This should be the title of this figure.",outer=TRUE)
> title(main="This should be the title of this figure.")
>
>   Please, let me know if I can be of any further help in tracing down
> the problem.
>
> Thanks,
> Patrick
>
> PS: Note that there is for the moment a work around which is the
> following:
>
> # Work-around
> par(mfrow=c(2,2),oma=c(0,0,4,0))
> plot(1:3,1:3,xlab="This is the x-axis label.",
>      ylab="This is the y-axis label.",main="a)")
> par(mfrow=c(1,1),oma=c(0,0,0,0))
> mtext("This should be the title of this figure.",line=2,font=2,cex=1.2)
>
> -----------------------------------------------------------------
>
> > R.version
>          _
> platform i686-pc-linux-gnu
> arch     i686
> os       linux-gnu
> system   i686, linux-gnu
> status
> major    1
> minor    5.1
> year     2002
> month    06
> day      17
> language R
>
> > R.version
>          _
> platform alphaev6-dec-osf4.0f
> arch     alphaev6
> os       osf4.0f
> system   alphaev6, osf4.0f
> status
> major    1
> minor    5.0
> year     2002
> month    04
> day      29
> language R
>
> > R.version
>          _
> platform mips-sgi-irix6.5
> arch     mips
> os       irix6.5
> system   mips, irix6.5
> status
> major    1
> minor    5.0
> year     2002
> month    04
> day      29
> language R
>
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-- 
Brian D. Ripley,                  ripley@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 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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The title function does not always work properly when used to add a global title to a figure containing several plots.
ripley@stats.ox.ac.uk