[R] Getting tick positions

[Paul Murrell]

Hi


Uwe Ligges wrote:
> Jim Lemon wrote:
> 
>> Thanks for the answers - I should have been more specific as I had 
>> already tried axTicks and pretty.
>>
>> The function in question is gantt.chart() in the latest plotrix 
>> package (Thanks to Scott Waichler for the original code). I settled on 
>> axis.POSIXct as it seemed the most appropriate for this function, but 
>> couldn't find a way to get the positions of the ticks so that I could 
>> then draw grid lines along the months|days|hours. While the trick of 
>> copying the original function works, I wondered why the axis* 
>> functions don't return the tick positions as barplot returns the bar 
>> positions. Is there any reason not to return "z", or is it just 
>> historical?
> 
> 
> I think historical.
> 
> Replacing
>     return R_NilValue;
> by
>     return at;
> in do_axis (plot.c) should do the trick (well, I'm a bit afraid 
> concerning the UNPROTECT, you might need to do that later, after the 
> recording stuff?).


Thanks for the suggestion Uwe (you were right about the UNPROTECT).
This change is now in the development version of R.

Paul
-- 
Dr Paul Murrell
Department of Statistics
The University of Auckland
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