R help - Aug 2007 - "Cut marks" on a plot's y-axis to indicate it is a truncated axis

Hi,

I've plotted a Kaplan-Meier curve but the curves only range from 0.7 to
1 on the y-axis. Therefore I have used: -

ylim=c(0.7,1)

[although I think convention dictates that you plot 0.5 to 1 to show the
median? A few papers I've read have done this]??

BUT, I would like a symbol like // (but rotated 90 degrees) to indicate
that the y-axis has been truncated. I'd need to be able to specify
exactly where on the axis to put the symbol as well.

I couldn't find anything under "par" or "plot" for doing
this

Thanks for any help,

DaveL



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Hi,

I've plotted a Kaplan-Meier curve but the curves only range from 0.7 to
1 on the y-axis. Therefore I have used: -

ylim=c(0.7,1)

[although I think convention dictates that you plot 0.5 to 1 to show the
median? A few papers I've read have done this]??

BUT, I would like a symbol like // (but rotated 90 degrees) to indicate
that the y-axis has been truncated. I'd need to be able to specify
exactly where on the axis to put the symbol as well.

I couldn't find anything under "par" or "plot" for doing
this

Thanks for any help,

DaveL



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David Lloyd wrote:
> Hi,
> 
> I've plotted a Kaplan-Meier curve but the curves only range from 0.7 to
> 1 on the y-axis. Therefore I have used: -
> 
> ylim=c(0.7,1)
> 
> [although I think convention dictates that you plot 0.5 to 1 to show the
> median? A few papers I've read have done this]??
> 
> BUT, I would like a symbol like // (but rotated 90 degrees) to indicate
> that the y-axis has been truncated. I'd need to be able to specify
> exactly where on the axis to put the symbol as well.
> 
> I couldn't find anything under "par" or "plot" for
doing this
> 
Hi David,
Try looking for axis.break in the plotrix package.

Jim

--- David Lloyd <DavidLloyd at mail2lloyd.com> wrote:
> Hi,
> 
> I've plotted a Kaplan-Meier curve but the curves
> only range from 0.7 to
> 1 on the y-axis. Therefore I have used: -
> 
> ylim=c(0.7,1)
> 
> [although I think convention dictates that you plot
> 0.5 to 1 to show the
> median? A few papers I've read have done this]??
> 
> BUT, I would like a symbol like // (but rotated 90
> degrees) to indicate
> that the y-axis has been truncated. I'd need to be
> able to specify
> exactly where on the axis to put the symbol as well.
> 
> I couldn't find anything under "par" or "plot" for
> doing this
> 
> Thanks for any help,
> 
> DaveL
I think Jim Lemon's anwsered the question but why do
you need a cut?  There is no need to have a zero on
the plot unless it is some quirky style matter for the
journal.  

Any literate scientific reader should be able to
understand that the y-axis runs from .5 to 1 or
whatever.  Adding a zero point and the || simply is
what Tufte would call chart junk.