[R] simplify a data frame

[Tord Snall]

Dear all,
For the past three hours I have tried simplify a data frame. I would be
really happy if someone could help solving this, I'm sure simple, problem.

I want to "aggregate" the data frame:

ObjektID	BalteNummer	Baltessegment
S.13	S.13.1		S.13.1.2
S.13	S.13.1		S.13.1.3
S.13	S.13.2		S.13.2.1
S.13	S.13.2		S.13.2.2
S.13	S.13.2		S.13.2.3
S.13	S.13.3		S.13.3.6
S.13	S.13.3		S.13.3.7
S.13	S.13.3		S.13.3.8
S.13	S.13.3		S.13.3.9


so that the results look likte this:


ObjektID	BalteNummer	
S.13	S.13.1
S.13	S.13.2
S.13	S.13.3

There are in fact many ObjektID.


Thanks in advance!


Sincerely
Tord

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Tord Snäll
Avd. f växtekologi, Evolutionsbiologiskt centrum, Uppsala universitet
Dept. of Plant Ecology, Evolutionary Biology Centre, Uppsala University
Villavägen 14			
SE-752 36 Uppsala, Sweden
Tel: 018-471 28 82 (int +46 18 471 28 82) (work)
Tel: 018-25 71 33 (int +46 18 25 71 33) (home)
Fax: 018-55 34 19 (int +46 18 55 34 19) (work)
E-mail: Tord.Snall at ebc.uu.se
Check this: http://www.vaxtbio.uu.se/resfold/snall.htm!
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