R devel - Aug 2009 - Wishlist: specify the border color of boxes in legend() (PR#13913)

I could not find a way to specify the border color of the boxes drawn in
a legend, so that the legend can match exactly the colors of the actual
plot (e.g. in the case of two superimposed histograms which have
different shading and different borders).

Indeed, the legend function seems to hard code the color "black" for
the
borders in this call:

         rect2(left = xt, top = yt + ybox/2, dx = xbox, dy = ybox,
               col = fill, density = density, angle = angle,
                border = "black")

I worked around this by adding a "border" argument to the function
(which defaults to "black"), and changing the call above. It works for
me; I have looked quickly at the rest of the function to see if there
would be a side effect and did not see any (but I haven't checked
carefully).

This could be a useful improvement of the legend() function; in case the
change described above looks usable, I attach two simple diff files (for
the function itself and the manual page).

Cheers,

Fr?d?ric

>>>>> "FS" == Frederic Schutz <Frederic.Schutz at
isb-sib.ch>
>>>>>     on Thu, 27 Aug 2009 13:25:16 +0200 (CEST) writes:
    FS> I could not find a way to specify the border color of the boxes drawn
in
    FS> a legend, so that the legend can match exactly the colors of the
actual
    FS> plot (e.g. in the case of two superimposed histograms which have
    FS> different shading and different borders).

    FS> Indeed, the legend function seems to hard code the color
"black" for the
    FS> borders in this call:

    FS> rect2(left = xt, top = yt + ybox/2, dx = xbox, dy = ybox,
    FS> col = fill, density = density, angle = angle,
    FS> border = "black")

    FS> I worked around this by adding a "border" argument to the
function
    FS> (which defaults to "black"), and changing the call above.
It works for
    FS> me; I have looked quickly at the rest of the function to see if there
    FS> would be a side effect and did not see any (but I haven't checked
    FS> carefully).

    FS> This could be a useful improvement of the legend() function; in case
the
    FS> change described above looks usable, I attach two simple diff files
(for
    FS> the function itself and the manual page).

    FS> Cheers,
    FS> Fr?d?ric

Thank you, Fr?d?ric,
indeed, the changes are so minimal that I will apply the two
patches and they should be in "R-devel" (for R 2.10.0) soon.

Best regards,
Martin Maechler, ETH Zurich


    FS> --------------040007030503070307040509
    FS> Content-Type: text/x-patch;
    FS> name="legend.R.diff"
    FS> Content-Transfer-Encoding: 7bit
    FS> Content-Disposition: inline;
    FS> filename="legend.R.diff"

    FS> --- legend.R~	2009-03-20 00:05:18.000000000 +0100
    FS> +++ legend.R	2009-08-27 11:52:02.000000000 +0200
    FS> @@ -15,8 +15,8 @@
    FS> #  http://www.r-project.org/Licenses/
 
    FS> legend <-
    FS> -function(x, y = NULL, legend, fill=NULL, col = par("col"),
lty, lwd, pch,
    FS> -	 angle = 45, density = NULL, bty = "o", bg =
par("bg"),
    FS> +function(x, y = NULL, legend, fill=NULL, col = par("col"),
border="black",
    FS> +         lty, lwd, pch, angle = 45, density = NULL, bty =
"o", bg = par("bg"),
    FS> box.lwd = par("lwd"), box.lty = par("lty"),
box.col = par("fg"),
    FS> pt.bg = NA, cex = 1, pt.cex = cex, pt.lwd = lwd,
    FS> xjust = 0, yjust = 1, x.intersp = 1, y.intersp = 1, adj = c(0, 0.5),
    FS> @@ -217,7 +217,7 @@
    FS> fill <- rep(fill, length.out = n.leg)
    FS> rect2(left = xt, top=yt+ybox/2, dx = xbox, dy = ybox,
    FS> col = fill,
    FS> -		  density = density, angle = angle, border = "black")
    FS> +		  density = density, angle = angle, border = border)
    FS> }
    FS> xt <- xt + dx.fill
    FS> }

    FS> --------------040007030503070307040509
    FS> Content-Type: text/x-patch;
    FS> name="legend.Rd.diff"
    FS> Content-Transfer-Encoding: 7bit
    FS> Content-Disposition: inline;
    FS> filename="legend.Rd.diff"

    FS> --- legend.Rd~	2009-03-20 00:05:18.000000000 +0100
    FS> +++ legend.Rd	2009-08-27 11:57:28.000000000 +0200
    FS> @@ -8,7 +8,7 @@
    FS> \title{Add Legends to Plots}
    FS> \usage{
    FS> legend(x, y = NULL, legend, fill = NULL, col = par("col"),
    FS> -       lty, lwd, pch,
    FS> +       border="black", lty, lwd, pch,
    FS> angle = 45, density = NULL, bty = "o", bg =
par("bg"),
    FS> box.lwd = par("lwd"), box.lty = par("lty"),
box.col = par("fg"),
    FS> pt.bg = NA, cex = 1, pt.cex = cex, pt.lwd = lwd,
    FS> @@ -34,6 +34,8 @@
    FS> with the specified colors (or shaded in the specified colors)
    FS> to appear beside the legend text.}
    FS> \item{col}{the color of points or lines appearing in the legend.}
    FS> +  \item{border}{the border color for the boxes (used only if
    FS> +    \code{fill} is specified).}
    FS> \item{lty, lwd}{the line types and widths for lines appearing in the
    FS> legend.  One of these two \emph{must} be specified for line drawing.}
    FS> \item{pch}{the plotting symbols appearing in the legend, either as

    FS> --------------040007030503070307040509--

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