R help - Oct 2010 - Line Type Specification: lty="<on><off>" but lty="<off><on>"?

Hi,

Section 'Line Type Specification' in help(par) explains how you can do
custom line types.  For example:

plot(NA, xlim=c(0,1), ylim=c(0,1));
abline(h=1/2, col="blue", lwd=2, lty="88");

will draw a dashed line segment where the line is composed of 8 units
of "on" (blue color) and 8 units of "off" (transparent),
then
repeated.

Now I'd like to draw a second red line overlapping this one, but where
the "gaps" are now red.  Technically, I think the following would
define that:

abline(h=1/2, col="red", lwd=2, lty="0880");

that is 0 "on", 8 "off", 8 "on" (red color) and 0
"off", then repeated.

However, zeros are not allowed (actually, why not?)

Any suggestions to draw one red and one blue dashed lines that, if
overlapping, the the overlapping segments will be blue, red, blue,
red, ...?

/Henrik

Tena koe Henrik

Not exactly what you are requesting but you could draw a solid line and then the
dashed line over the top:

plot(1:10, panel.first=abline(0, 1, col='red', lwd=2),
panel.last=abline(0, 1, col='blue', lty='88', lwd=2))

or

plot(1:10)
abline(0, 1, col='red', lwd=2)
abline(0, 1, col='blue', lty='88', lwd=2))

This may be system or graphics device dependent (I'm using Windows).

HTH ....

Peter Alspach
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Henrik Bengtsson
> Sent: Monday, 11 October 2010 10:50 a.m.
> To: r-help
> Subject: [R] Line Type Specification: lty="<on><off>"
but
> lty="<off><on>"?
> 
> Hi,
> 
> Section 'Line Type Specification' in help(par) explains how you can
do
> custom line types.  For example:
> 
> plot(NA, xlim=c(0,1), ylim=c(0,1));
> abline(h=1/2, col="blue", lwd=2, lty="88");
> 
> will draw a dashed line segment where the line is composed of 8 units
> of "on" (blue color) and 8 units of "off"
(transparent), then
> repeated.
> 
> Now I'd like to draw a second red line overlapping this one, but where
> the "gaps" are now red.  Technically, I think the following would
> define that:
> 
> abline(h=1/2, col="red", lwd=2, lty="0880");
> 
> that is 0 "on", 8 "off", 8 "on" (red color)
and 0 "off", then repeated.
> 
> However, zeros are not allowed (actually, why not?)
> 
> Any suggestions to draw one red and one blue dashed lines that, if
> overlapping, the the overlapping segments will be blue, red, blue,
> red, ...?
> 
> /Henrik
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
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On Oct 10, 2010, at 5:50 PM, Henrik Bengtsson wrote:
> Hi,
>
> Section 'Line Type Specification' in help(par) explains how you can
do
> custom line types.  For example:
>
> plot(NA, xlim=c(0,1), ylim=c(0,1));
> abline(h=1/2, col="blue", lwd=2, lty="88");
>
> will draw a dashed line segment where the line is composed of 8 units
> of "on" (blue color) and 8 units of "off"
(transparent), then
> repeated.
>
> Now I'd like to draw a second red line overlapping this one, but where
> the "gaps" are now red.  Technically, I think the following would
> define that:
>
> abline(h=1/2, col="red", lwd=2, lty="0880");
>
> that is 0 "on", 8 "off", 8 "on" (red color)
and 0 "off", then
> repeated.
>
> However, zeros are not allowed (actually, why not?)
>
> Any suggestions to draw one red and one blue dashed lines that, if
> overlapping, the the overlapping segments will be blue, red, blue,
> red, ...?
You might look at the code for color.scale.lines in package plotrix.  
It's not exactly what you asked for but Jim Lemon has figured out out  
how to change colors of connected segments.

-- 
David.
>
> /Henrik