[R] Grid lines

[Uwe Ligges]

Chris Li wrote:
> Hi everyone. I am new to R.
> 
> It will be greatly appreciated if someone can help me with the following
> questions.
> 
> Here's the graph I have just produced. 
> http://www.nabble.com/file/p24732839/calibration.jpeg 
> 
> (1) How can I put the legend on top of the grid lines?


It probably is on top. I guess you want white background as in:

legend(....., bg="white")


> (2) How can I match the grid lines with the x-axis ticks?


grid() does exactly that for me, so I guess you are not using base 
graphics, hence please provide reproducible code as the posting guide 
suggests!


> (3) How can I change the x-axis format from e.g. Mar, Apr...etc to
> 1-3-2009,1-4-2009...etc?


One way is to specify the x-axis separately, but since we do not know 
how you produced that plot ....

Uwe Ligges




> Many thanks! :-)
> 
> Chris