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 > *** > Le contenu de cet e-mail et de ses pi�ces jointes est destin� > � l'usage exclusif du > (des) destinataire(s) express�ment d�sign�(s) comme tel(s). > En cas de r�ception de cet > e-mail par erreur, le signaler � son exp�diteur et ne pas en > divulguer le contenu. > L'absence de virus a �t� v�rifi� � l'�mission du message. Il > convient n�anmoins de > v�rifier l'absence de corruption � sa r�ception. > > The contents of this email and any attachments are > confidential. They are intended for > the named recipient(s) only. If you have received this email > in error please notify the > system manager or the sender immediately and do not disclose > the contents to > anyone or make copies. eSafe scanned this email for viruses, > vandals and malicious > content. > *** > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html > > ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
