[Rd] legend -- one more try

[bolker@zoo.ufl.edu]

  Dermot MacSweeney pointed out to me that after my "fix" of legend(),
points were no longer coming out placed in the middle of the lines, but at
the right-hand edge.  It turns out that naively swapping the order of
point-drawing and line-drawing also messes up the bookkeeping that
legend() does on the current x-location.  Here's my patch, which fixes
that bookkeeping (and incidentally substitutes "seg.len" for 2 where it
refers to the length of the drawn line segments in units of x.char; one
could make seg.len user-settable, I don't know if it's worth the bother).

  This time the patch is against the current legend() in R-devel.

*** new-legend.R	Thu Oct 19 16:25:36 2000
--- R-devel/src/library/base/R/legend.R	Wed Sep  6 04:11:16 2000
***************
*** 141,171 ****
      }
      if(has.pch || do.lines)
          col <- rep(col,length.out=n.leg)
-     
-     if (do.lines) {                     #- draw lines ---------------------
-         seg.len <- 2 # length of drawn segment, in xchar units
- 	ok.l <- if(missing(lty)) { lty <- 1; TRUE } else lty > 0
- 	if(missing(lwd)) lwd <- par("lwd")
- 	lty <- rep(lty, length.out = n.leg)
- 	lwd <- rep(lwd, length.out = n.leg)
- 	if(trace)
- 	    catn("  segments2(",xt[ok.l] + x.off*xchar ,",", yt[ok.l],
-                  ", dx=",seg.len*xchar,", dy=0, ...)", sep="")
- 	segments2(xt[ok.l] + x.off*xchar, yt[ok.l], dx= seg.len*xchar, dy=0,
- 		  lty = lty[ok.l], lwd = lwd[ok.l], col = col[ok.l])
- 	# if (!merge)
-         xt <- xt + (seg.len+x.off) * xchar
-     }
      if (has.pch) {                      #- draw points -------------------
  	pch   <- rep(pch, length.out=n.leg)
  	pt.bg <- rep(pt.bg, length.out=n.leg)
  	ok <- is.character(pch) | pch >= 0
! 	x1 <- (if(merge) xt-(seg.len/2)*xchar else xt)[ok]
  	y1 <- yt[ok]
  	if(trace)
  	    catn("  points2(", x1,",", y1,", pch=", pch[ok],"...)")
  	points2(x1, y1, pch=pch[ok], col=col[ok], cex=cex, bg = pt.bg[ok])
  	if (!merge) xt <- xt + dx.pch
      }
  
      xt <- xt + x.intersp * xchar
--- 141,169 ----
      }
      if(has.pch || do.lines)
          col <- rep(col,length.out=n.leg)
      if (has.pch) {                      #- draw points -------------------
  	pch   <- rep(pch, length.out=n.leg)
  	pt.bg <- rep(pt.bg, length.out=n.leg)
  	ok <- is.character(pch) | pch >= 0
! 	x1 <- (if(merge) xt + 0.2*xchar else xt)[ok]
  	y1 <- yt[ok]
  	if(trace)
  	    catn("  points2(", x1,",", y1,", pch=", pch[ok],"...)")
  	points2(x1, y1, pch=pch[ok], col=col[ok], cex=cex, bg = pt.bg[ok])
  	if (!merge) xt <- xt + dx.pch
+     }
+     if (do.lines) {                     #- draw lines ---------------------
+ 	ok.l <- if(missing(lty)) { lty <- 1; TRUE } else lty > 0
+ 	if(missing(lwd)) lwd <- par("lwd")
+ 	lty <- rep(lty, length.out = n.leg)
+ 	lwd <- rep(lwd, length.out = n.leg)
+ 	if(trace)
+ 	    catn("  segments2(",xt[ok.l] + x.off*xchar ,",", yt[ok.l],
+                  ", dx=",2*xchar,", dy=0, ...)", sep="")
+ 	segments2(xt[ok.l] + x.off*xchar, yt[ok.l], dx= 2*xchar, dy=0,
+ 		  lty = lty[ok.l], lwd = lwd[ok.l], col = col[ok.l])
+ 	## if (!merge)
+         xt <- xt + (2+x.off) * xchar
      }
  
      xt <- xt + x.intersp * xchar

-- 
318 Carr Hall                                bolker@zoo.ufl.edu
Zoology Department, University of Florida    http://www.zoo.ufl.edu/bolker
Box 118525                                   (ph)  352-392-5697
Gainesville, FL 32611-8525                   (fax) 352-392-3704

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