R help - Jul 2006 - How to change the type of segments ends?

Hi,

I am trying to plot odds ratios and the corresponding confidence
intervals in horizontal segments. It would be ideal if the confidence
interval segment can be drawn with little vertical bars at both ends. I
have tried very hard to change the type of ends by using 'lend'
arguments, but cannot make it. I even tried 'arrows()', but still
failed. Following is the code I use:
===================================================drug.or <-
c(1.017,1.437,1.427,2.211)
drug.orl <- c(0.715,1.075,1.103,1.696)
drug.oru <- c(1.446,1.922,1.845,2.882)

yaxis <- seq(1,4,by=1)

plot(x=drug.or,y=yaxis,type='p',pch=17,xlim=c(0,3),axes=FALSE,
     xlab='Odds Ratio',ylab='',main='Reference Group: A
only')
axis(1,at=seq(0,3,by=0.5),labels=paste(seq(0,3,by=0.5)))
axis(2,at=yaxis,las=2)


segments(x0=drug.orl,x1=drug.oru,y0=yaxis,y1=yaxis,col=4,lend=2)

# or try
#arrows(x0=drug.orl,x1=drug.oru,y0=yaxis,y1=yaxis,length=0.1,angle=0,cod
e=3,col=4,lend=2)

box()
====================================================

Any comments or suggestions would be greatly appreciated.


Jane

University of Pittsburgh
Pittsburgh, PA 15261

On Fri, 2006-07-07 at 11:47 -0400, Lu, Jiang Jane wrote:
> Hi,
> 
> I am trying to plot odds ratios and the corresponding confidence
> intervals in horizontal segments. It would be ideal if the confidence
> interval segment can be drawn with little vertical bars at both ends. I
> have tried very hard to change the type of ends by using 'lend'
> arguments, but cannot make it. I even tried 'arrows()', but still
> failed. Following is the code I use:
> ===================================================> drug.or <-
c(1.017,1.437,1.427,2.211)
> drug.orl <- c(0.715,1.075,1.103,1.696)
> drug.oru <- c(1.446,1.922,1.845,2.882)
> 
> yaxis <- seq(1,4,by=1)
> 
> plot(x=drug.or,y=yaxis,type='p',pch=17,xlim=c(0,3),axes=FALSE,
>      xlab='Odds Ratio',ylab='',main='Reference Group: A
only')
> axis(1,at=seq(0,3,by=0.5),labels=paste(seq(0,3,by=0.5)))
> axis(2,at=yaxis,las=2)
> 
> 
> segments(x0=drug.orl,x1=drug.oru,y0=yaxis,y1=yaxis,col=4,lend=2)
> 
> # or try
> #arrows(x0=drug.orl,x1=drug.oru,y0=yaxis,y1=yaxis,length=0.1,angle=0,cod
> e=3,col=4,lend=2)
> 
> box()
> ====================================================
Try this using arrows():

drug.or <- c(1.017,1.437,1.427,2.211)
drug.orl <- c(0.715,1.075,1.103,1.696)
drug.oru <- c(1.446,1.922,1.845,2.882)

yaxis <- seq(1, 4, by=1)

plot(drug.or, yaxis ,type='p', pch=17, xlim=c(0,3), axes=FALSE,
     xlab='Odds Ratio', ylab='', main='Reference Group: A
only')

axis(1, at=seq(0,3,by=0.5), labels=paste(seq(0,3,by=0.5)))
axis(2, at=yaxis, las=2)

arrows(drug.orl, yaxis, drug.oru, yaxis, angle=90,
       length=0.1, code=3, col=4, lend=2)


You need to specify an angle of 90 degrees to get the arrow heads to be
perpendicular to the primary line segment. An angle of 0 superimposes
the heads on the primary line segment, so they don't show.

HTH,

Marc Schwartz

You need angle=90. From the help page:

    angle: angle from the shaft of the arrow to the edge of the arrow
           head.


On Fri, 7 Jul 2006, Lu, Jiang Jane wrote:
> Hi,
>
> I am trying to plot odds ratios and the corresponding confidence
> intervals in horizontal segments. It would be ideal if the confidence
> interval segment can be drawn with little vertical bars at both ends. I
> have tried very hard to change the type of ends by using 'lend'
> arguments, but cannot make it. I even tried 'arrows()', but still
> failed. Following is the code I use:
> ===================================================> drug.or <-
c(1.017,1.437,1.427,2.211)
> drug.orl <- c(0.715,1.075,1.103,1.696)
> drug.oru <- c(1.446,1.922,1.845,2.882)
>
> yaxis <- seq(1,4,by=1)
>
> plot(x=drug.or,y=yaxis,type='p',pch=17,xlim=c(0,3),axes=FALSE,
>     xlab='Odds Ratio',ylab='',main='Reference Group: A
only')
> axis(1,at=seq(0,3,by=0.5),labels=paste(seq(0,3,by=0.5)))
> axis(2,at=yaxis,las=2)
>
>
> segments(x0=drug.orl,x1=drug.oru,y0=yaxis,y1=yaxis,col=4,lend=2)
>
> # or try
> #arrows(x0=drug.orl,x1=drug.oru,y0=yaxis,y1=yaxis,length=0.1,angle=0,cod
> e=3,col=4,lend=2)
>
> box()
> ====================================================>
>
> Any comments or suggestions would be greatly appreciated.
>
>
> Jane
>
> University of Pittsburgh
> Pittsburgh, PA 15261
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
>
-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

Lu, Jiang Jane wrote:
> Hi,
> 
> I am trying to plot odds ratios and the corresponding confidence
> intervals in horizontal segments. It would be ideal if the confidence
> interval segment can be drawn with little vertical bars at both ends. I
> have tried very hard to change the type of ends by using 'lend'
> arguments, but cannot make it. I even tried 'arrows()', but still
> failed. Following is the code I use:
> ===================================================> drug.or <-
c(1.017,1.437,1.427,2.211)
> drug.orl <- c(0.715,1.075,1.103,1.696)
> drug.oru <- c(1.446,1.922,1.845,2.882)
> 
> yaxis <- seq(1,4,by=1)
> 
> plot(x=drug.or,y=yaxis,type='p',pch=17,xlim=c(0,3),axes=FALSE,
>      xlab='Odds Ratio',ylab='',main='Reference Group: A
only')
> axis(1,at=seq(0,3,by=0.5),labels=paste(seq(0,3,by=0.5)))
> axis(2,at=yaxis,las=2)
> 
> 
> segments(x0=drug.orl,x1=drug.oru,y0=yaxis,y1=yaxis,col=4,lend=2)
> 
> # or try
> #arrows(x0=drug.orl,x1=drug.oru,y0=yaxis,y1=yaxis,length=0.1,angle=0,cod
> e=3,col=4,lend=2)
   The call to arrows() seems to do what you want if angle=90.  Also the 
lend argument seems unnecessary if you have angle=90.
> box()
> ====================================================> 
> 
> Any comments or suggestions would be greatly appreciated.
> 
> 
> Jane
> 
> University of Pittsburgh
> Pittsburgh, PA 15261
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
-- 
Chuck Cleland, Ph.D.
NDRI, Inc.
71 West 23rd Street, 8th floor
New York, NY 10010
tel: (212) 845-4495 (Tu, Th)
tel: (732) 512-0171 (M, W, F)
fax: (917) 438-0894

On Fri, 2006-07-07 at 11:47 -0400, Lu, Jiang Jane wrote:
> Hi,
> 
> I am trying to plot odds ratios and the corresponding confidence
> intervals in horizontal segments. It would be ideal if the confidence
> interval segment can be drawn with little vertical bars at both ends. I
> have tried very hard to change the type of ends by using 'lend'
> arguments, but cannot make it. I even tried 'arrows()', but still
> failed. Following is the code I use:
> ===================================================> drug.or <-
c(1.017,1.437,1.427,2.211)
> drug.orl <- c(0.715,1.075,1.103,1.696)
> drug.oru <- c(1.446,1.922,1.845,2.882)
> 
> yaxis <- seq(1,4,by=1)
> 
> plot(x=drug.or,y=yaxis,type='p',pch=17,xlim=c(0,3),axes=FALSE,
>      xlab='Odds Ratio',ylab='',main='Reference Group: A
only')
> axis(1,at=seq(0,3,by=0.5),labels=paste(seq(0,3,by=0.5)))
> axis(2,at=yaxis,las=2)
> 
> 
> segments(x0=drug.orl,x1=drug.oru,y0=yaxis,y1=yaxis,col=4,lend=2)
> 
> # or try
> #arrows(x0=drug.orl,x1=drug.oru,y0=yaxis,y1=yaxis,length=0.1,angle=0,cod
> e=3,col=4,lend=2)
> 
> box()
> ====================================================> 
> 
> Any comments or suggestions would be greatly appreciated.
> 
> 
> Jane
Hi Jane,

Thanks for the reproducible example. Why do you think lend will do what
you want? From ?par:

'lend' The line end style.  This can be specified as an integer or
          string:

          '0' and '"round"' mean rounded line caps
[_default_];

          '1' and '"butt"' mean butt line caps;

          '2' and '"square"' mean square line caps.

          As from R 2.3.0 this can be specified inline.

This is talking about line endings - do you want hard or soft line ends
or type of joins in line segments? It does not mean the type of line
endings you might get in Adobe Illustrator or Inkscape vector drawing
packages.

You were close with arrows:

drug.or <- c(1.017,1.437,1.427,2.211)
drug.orl <- c(0.715,1.075,1.103,1.696)
drug.oru <- c(1.446,1.922,1.845,2.882)

yaxis <- seq(1,4,by=1)

plot(x = drug.or, y = yaxis, pch=17, xlim = c(0,3), axes=FALSE,
     xlab = 'Odds Ratio', ylab = '', main = 'Reference
Group: A only')
labs <- seq(0, 3, by = 0.5)
axis(1, at = labs, labels = labs)
axis(2, at = yaxis, las = 2)
arrows(x0 = drug.orl, x1 = drug.oru, y0 = yaxis, y1 = yaxis, length=0.1,
code = 3, col = 4, angle = 90)

the angle argument is the key. See arrows? You don't need lend at all to
do what you want.

HTH

G

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