R devel - May 2001 - legend() with xpd=T; omission of initial plot character (PR#943)

In the following:

plot(0:1, 0:1)
legend(x=0, y=1.2, pch=c(1,2), legend=c("May","June"))

the first plot character is omitted when plotting to
the screen.

I obtained the same behaviour when placing a legend
in the margin following use of pairs()

-please do not edit the information below--

Version:
  platform = i386-pc-mingw32
  arch = x86
  os = Win32
  system = x86, Win32
  status   major = 1
  minor = 2.3
  year = 2001
  month = 04
  day = 26
  language = R

Windows 98 SE 4.10 (build 2222)  A

Search Path:
  .GlobalEnv, package:ctest, Autoloads, package:base
John Maindonald               email : john.maindonald@anu.edu.au
Statistical Consulting Unit,  phone : (6125)3998
c/o CMA, SMS,                 fax   : (6125)5549
John Dedman Mathematical Sciences Building
Australian National University
Canberra ACT 0200
Australia


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Hi

Bug summary:----
par(xpd=T)
plot(0:1, 0:1)
legend(x=0, y=1.2, pch=c(1,2), legend=c("May","June"))

the first plot character is omitted when plotting to
the screen.
Bug summary:----

I cannot reproduce this bug, BUT it did show up a bug in rect() -- in the
example above, the border around the legend is not drawn.

This is because rect() ignores par(xpd).  The default is rect(xpd=FALSE).  This
is at odds with text(xpd=NULL) and polygon(xpd=NULL) which use par(xpd) by
default.  arrows(xpd=FALSE) has the same problem as rect().  

I propose modifying rect() and arrows() to use par(xpd) by default like text()
and polygon().  There will, as usual, be a small risk that someone's code
will
produce different output after this change, but this risk should be pretty
small.

Any objections ... ?

Paul


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>>>>> "Paul" == Paul Murrell
<paul@stat.auckland.ac.nz> writes:
    Paul> Hi
    Paul> Bug summary:----
    Paul> par(xpd=T)
    Paul> plot(0:1, 0:1)
    Paul> legend(x=0, y=1.2, pch=c(1,2),
legend=c("May","June"))

    Paul> the first plot character is omitted when plotting to
    Paul> the screen.
    Paul> Bug summary:----

    Paul> I cannot reproduce this bug, BUT it did show up a bug in rect()
    Paul> -- in the example above, the border around the legend is not
    Paul> drawn.

Coincidence, I *did* look at that bug only yesterday.
My experience:
   I *could* reproduce the bug {X11(), Linux-386}, but only a few times. 
   Then, it didn't show anymore. Even restarting R wouldn't show it
again.
   My ``explanation'' was that it might be (a bug) inside X11 / Window
manager
   handling of things... ??


    Paul> This is because rect() ignores par(xpd).  The default is
    Paul> rect(xpd=FALSE).  This is at odds with text(xpd=NULL) and
    Paul> polygon(xpd=NULL) which use par(xpd) by default.
    Paul> arrows(xpd=FALSE) has the same problem as rect().

    Paul> I propose modifying rect() and arrows() to use par(xpd) by
    Paul> default like text() and polygon().  There will, as usual, be a
    Paul> small risk that someone's code will produce different output
    Paul> after this change, but this risk should be pretty small.

    Paul> Any objections ... ?

not at all, but please fix  abline(*) at the same time.
It doesn't obey xpd either (PR#750).

Martin

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