Hi Greg, thanks for your help. I found vectorFields, as suggested by Jim
Lemon, in plotrix to be slightly easier (given my relatively basic R
language knowledge!). Kind Regards, Conor


On 27 September 2013 22:07, Greg Snow <538280@gmail.com> wrote:

> The ms.arrows along with my.symbols in the TeachingDemos package does not
> require start and end points, it takes a single point along with the angle
> and length (and the length can be a single constant to have all the arrows
> the same length, or a variable to have different lengths).  You can also
> set an adjustment parameter to decide if the arrows should be centered on
> the point, start at the point, or end at the point.
>
> The ms.arrows function was designed for exactly what you describe.
>
>
> On Fri, Sep 27, 2013 at 12:56 PM, Conor Ryan <miolmor@gmail.com> wrote:
>
>> I am trying to plot points on a map for each ship locations (lat/long),
>> where
>> each point is a line whose angle (degrees) denotes ships heading and whose
>> line length denotes it's speed. Unfortunately arrows(); p.arrows (sfsmisc)
>> and ms.arrows (TeachingDemos) require start and end coordinates but I only
>> have a single coordinate and an angle to work with. Can you suggest any
>> other packages or commands that might allow me to plot this?
>> Alternatively,
>> can anyone suggest a method of making 'angle' a vector quantity when using
>> the arrows function? Any advice would be much appreciated!
>>
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>>
>>
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>
>
>
> --
> Gregory (Greg) L. Snow Ph.D.
> 538280@gmail.com
>

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