Just a wild guess (not using 2.7.0): maybe there is some memory
allocation going on Quartz-internally, and the block size has changed
between Tiger and Leopard?
The following sample code from apple might be related, it shows and
measures performance of 4 different ways of drawing lines: (1) as
separate CGPaths, (2) as a single CGPath, (3) using the new bulk line
drawing function in Tiger, and (4) by limiting the number of lines
drawn: http://beta.devworld.apple.com/samplecode/QuartzLines/
QuartzLines.zip
In a nutshell,
(1) for() { CGContextBeginPath(); CGContextMoveToPoint();
CGContextAddLineToPoint(); CGContextStrokePath(); }
(2) CGPathCreateMutable(); CGPathMoveToPoint(); for ()
{ CGPathAddLineToPoint(); }
(3) /* construct point array in memory, then */
CGContextStrokeLineSegments();
(4) as (3), but use fewer points. not quite as accurate due to
undersampling
On my system, benchmark results are
(1) 28.1 ms (10000 lines, 356k lines/sec)
(2) 4.9 ms (10000 lines, 2053k lines/sec)
(3) 4.0 ms (10000 lines, 2484k lines/sec)
(4) 1.6 ms (898 lines, 561k lines/sec)
The current approach used in RQuartz_Polylines, (1), seems to be
slower than what can be achieved by, e.g., using (2) or (3).
On Apr 27, 2008, at 16:36, Tomas Mikoviny wrote:
OK I've checked the RQuartz_Polyline and RQuartz_Polygon. Its quite
straight forward. However I don't see anything causing problem we
discuss.
tomas
# Revision 45515: /branches/R-2-7-branch/src/library/grDevices/src
-----------
static void RQuartz_Polyline(int n, double *x, double *y, CTXDESC)
{
if (n < 2) return;
int i;
DRAWSPEC;
if (!ctx) NOCTX;
SET(RQUARTZ_STROKE | RQUARTZ_LINE);
CGContextBeginPath(ctx);
CGContextMoveToPoint(ctx, x[0], y[0]);
for(i = 1 ; i < n; i++)
CGContextAddLineToPoint(ctx, x[i], y[i]);
CGContextStrokePath(ctx);
}
static void RQuartz_Polygon(int n, double *x, double *y, CTXDESC)
{
if (n < 2) return;
int i;
DRAWSPEC;
if (!ctx) NOCTX;
SET(RQUARTZ_FILL | RQUARTZ_STROKE | RQUARTZ_LINE);
CGContextBeginPath(ctx);
CGContextMoveToPoint(ctx, x[0], y[0]);
for(i = 1; i < n; i++)
CGContextAddLineToPoint(ctx, x[i], y[i]);
CGContextClosePath(ctx);
CGContextDrawPath(ctx, kCGPathFillStroke);
}
------------
On 27 Apr 2008, at 15:08, Prof Brian Ripley wrote:
Some versions of Windows GDI have a superficially identical problem
-- stroking a path is quadratic in the number of segments. The
solution we used (in gdrawpolyline, in src/extra/graphapp/gdraw.c)
was to split the drawing into pieces of length 1000, and that could
be used here. It would be a simple modification to RQuartz_Polyline
and RQuartz_Polygon, so please try it and let us know how you get on.
It would also have been helpful to (C-level) profile the call and
find out where the time is being spent -- I expect it not to be in R
at all but in Quartz.
On Sun, 27 Apr 2008, Tomas Mikoviny wrote:
I found where is the problem, however have no solution for it right
now.
To demonstrate (I have chosen 6000 to match my datasets size):
x=seq(1:6000)
y=rnorm(6000)
plot(x,y)
Absolutely no problem until now, everything is responsive, no lags.
Problem appears when I insert parameter 'type':
slowdown and unacceptable lag for "l", "o", "s"
plot(x,y, type="l")
plot(x,y, type="o")
...
however no problem at all (instantly plotted) for "p", "b", "c",
"h"
plot(x,y, type="p")
plot(x,y, type="b")
...
Does anyone know possible reason for this behaviour. Once again, I
use
clear install of R version 2.7.0 (2008-04-22). When I try the same
stuff with latest 2.6.2 version everything runs smoothly without any
problems.
tomas
On 27 Apr 2008, at 10:49, Charles Hebert wrote:
Hi all,
I've the same problem + the resizing of the window is really really
slow... for all datasets. I'm running leopard 10.5.2 and the latest
macOS R dmg.
For all datasets. But when i use quartz() then plot, it seems ok
(slow again but... usable). So right now, i use quartz(file,
type="pdf")...
Best regards,
Charles
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Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
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