[R] computing differences between consecutive vector elements

[Liaw, Andy]

Not exactly sure what you want, but seems like you can sort the data frame
by `t', then do diff() on the x, y, and z columns.

Andy

> From: Dewez Thomas
> 
> Dear R-users,
> 
> I am a newbie to R so please excuse this naive question for 
> which I couldn't
> seem to find online answers.
> 
> I have this data frame containing a series of locations through time
> (x,y,z,t). I would like to compute the difference in x, y and 
> z between t-1
> and t.
> 
> Sounds easy enough, but how on earth does one loop through 
> vector elements
> and compute this difference?
> 
> Thanks
> 
> Thomas
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