R help - Jan 2009 - identifying what labels have been created in a plot

Colleagues

R 2.8.0; OS X, Vista, Ubuntu Linux

In some instances, when I create a graphic using plot(XVAR, YVAR), it  
would be valuable to know the values that R will display on the y-axis  
(e.g., if the range of data is 0-70, it might display 0, 10, 30, 50,  
70).   Is there a simple means to access these values?

Also, in some instances, additional ticks appear between the displayed  
values (in this case, at 20, 40, 60).  Can I obtain the list of the  
positions of all ticks?

Access to this information permits me to tailor the ticks and labels  
in a particular manner.

Thanks for any suggestions.

Dennis


Dennis Fisher MD
P < (The "P Less Than" Company)
Phone: 1-866-PLessThan (1-866-753-7784)
Fax: 1-415-564-2220
www.PLessThan.com

on 01/30/2009 10:51 AM Dennis Fisher wrote:
> Colleagues
> 
> R 2.8.0; OS X, Vista, Ubuntu Linux
> 
> In some instances, when I create a graphic using plot(XVAR, YVAR), it
> would be valuable to know the values that R will display on the y-axis
> (e.g., if the range of data is 0-70, it might display 0, 10, 30, 50,
> 70).   Is there a simple means to access these values?
> 
> Also, in some instances, additional ticks appear between the displayed
> values (in this case, at 20, 40, 60).  Can I obtain the list of the
> positions of all ticks?
> 
> Access to this information permits me to tailor the ticks and labels in
> a particular manner.
> 
> Thanks for any suggestions.
> 
> Dennis
See ?axis, where in the Details, it will lead you to ?axTicks

plot(c(0, 70), c(0, 70))

# Y axis tick marks
> axTicks(2)
[1]  0 10 20 30 40 50 60 70


pretty() will also get you similar information, save when using log scaling:
> pretty(c(0, 70))
[1]  0 10 20 30 40 50 60 70


Keep in mind that you can always explicitly call axis() using the 'at'
argument to specify the locations of the tick marks and labels, after
plotting something without the axes being drawn by default.

HTH,

Marc Schwartz

It might be easier to generate the plot without the y-axis and then
add you data with 'axis' using whatever tick marks you want.

On Fri, Jan 30, 2009 at 11:51 AM, Dennis Fisher <fisher at plessthan.com>
wrote:
> Colleagues
>
> R 2.8.0; OS X, Vista, Ubuntu Linux
>
> In some instances, when I create a graphic using plot(XVAR, YVAR), it would
> be valuable to know the values that R will display on the y-axis (e.g., if
> the range of data is 0-70, it might display 0, 10, 30, 50, 70).   Is there
a
> simple means to access these values?
>
> Also, in some instances, additional ticks appear between the displayed
> values (in this case, at 20, 40, 60).  Can I obtain the list of the
> positions of all ticks?
>
> Access to this information permits me to tailor the ticks and labels in a
> particular manner.
>
> Thanks for any suggestions.
>
> Dennis
>
>
> Dennis Fisher MD
> P < (The "P Less Than" Company)
> Phone: 1-866-PLessThan (1-866-753-7784)
> Fax: 1-415-564-2220
> www.PLessThan.com
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?

You might want to look at the pretty function. The code that I have  
seen often calls that function for the creation of axis tick levels  
with min and max as arguments. And its help page suggests that axTicks  
may give you exactly what you were seeking.

-- 
David Winsemius

On Jan 30, 2009, at 11:51 AM, Dennis Fisher wrote:
> Colleagues
>
> R 2.8.0; OS X, Vista, Ubuntu Linux
>
> In some instances, when I create a graphic using plot(XVAR, YVAR),  
> it would be valuable to know the values that R will display on the y- 
> axis (e.g., if the range of data is 0-70, it might display 0, 10,  
> 30, 50, 70).   Is there a simple means to access these values?
>
> Also, in some instances, additional ticks appear between the  
> displayed values (in this case, at 20, 40, 60).  Can I obtain the  
> list of the positions of all ticks?
>
> Access to this information permits me to tailor the ticks and labels  
> in a particular manner.
>
> Thanks for any suggestions.
>
> Dennis
>
>
> Dennis Fisher MD
> P < (The "P Less Than" Company)
> Phone: 1-866-PLessThan (1-866-753-7784)
> Fax: 1-415-564-2220
> www.PLessThan.com
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.