[R] Calculate geographic/euclidian distance between consecutive XY-pairs

[Johannes Radinger]

Hi Ray,

thank you very much. That one-line approach is what I was looking for.
A very simple but very efficient way without loading any other packages.

/j

On Tue, Dec 18, 2012 at 11:17 AM, Ray Brownrigg
<Ray.Brownrigg at ecs.vuw.ac.nz> wrote:
> On 18/12/2012 10:56 p.m., Johannes Radinger wrote:
>>
>> Hi,
>>
>> I have a dataframe containing 3 columns:
>>
>> data.frame(X=c(100,102,104,102,103),Y=c(12,14,14,13,16),Time=c(1,2,3,4,5))
>>
>> where X and Y are coordinates and "Time" refers to an index of a timestep.
>> Now I would like to get the distance between the consecutive timesteps.
>>
>> This should actually provide a vector of length=4, representing the
>> euclidian
>> resp. geopgraphic distance between the first and the second, and the
>> second
>> and the third timestep and so on...
>>
>> Is there a simple way to calculate this and get the resulting vector
>> as a result?
>> Or can anyone give an example?
>
> How about something like:
> coords <-
> data.frame(X=c(100,102,104,102,103),Y=c(12,14,14,13,16),Time=c(1,2,3,4,5))
> with(coords, sqrt(diff(X)^2 + diff(Y)^2))
>
> Ray Brownrigg
>>
>>
>> best regards,
>> /j
>>
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>
>
>