[R] How to draw a line in plot when I know the start point(x

[(Ted Harding)]

On 25-Jun-09 18:38:37, Marc Schwartz wrote:
> On Jun 25, 2009, at 1:30 PM, Lesandro wrote:
>> Hello all,
>> How to draw a line in plot when I know the start point(x1,y1)
>> and end point(x2,y2)? I need make this as additional information
>> in the graph:
>>
>> plot(wl2[[1]],wl2[[2]])
>>
>> I think that is possible make this with the function abline(), is  
>> possible? I looked the function lines() too, but don't understand
>> as make.
>>
>> Thanks!
>> Lesandro
> 
> See ?segments which does just what you are looking for.
> 
> lines() is more designed for a series of connected lines (eg. a  
> polygon) rather than a single line segment.
> 
> abline() can draw a straight line, at a given vertical or horizontal  
> position, or if given a linear model object, the fitted line.
> HTH,
> Marc Schwartz

Hmm ... for this particular purpose I don't see what is wrong with

  plot(wl2[[1]],wl2[[2]])
  lines(c(x1,x2),c(y1,y2))

along with any additional paramaters to lines() for line-type,
colour, etc. -- I do this all the time ...
Ted.

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Date: 25-Jun-09                                       Time: 19:51:20
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