say 'dat' is your data frame, then one way is the following:
f - factor(dat$Id, levels = unique(dat$Id))
dat$Number - unclass(f)
dat
I hope it helps.
Best,
Dimitris
clion wrote:
Dear R users,
my dataframe looks like this
head(dat)
Id sex byear age
1 300 m 2003 50
2 300 m 2003 36
3 402f 2003 29
4 402f 2003 21
5 402f 2003 64
6 150 m 2005 43
...
...(where Id is just the Identification number of Individual, sex (male or
female), byear (=birthyear))
now, I 'd like to add a column, where each Individual gets an automated
number starting from 1, so that I can number them consecutively
something which should look like this:
Id sex byear age Number
1 300 m 2003 50 1
2 300 m 2003 36 1
3 402f 2003 29 2
4 402f 2003 21 2
5 402f 2003 64 2
6 150 m 2005 43 3
...
...
how can I easily do this?
thanks a lot for any help,
Birte
--
Dimitris Rizopoulos
Assistant Professor
Department of Biostatistics
Erasmus University Medical Center
Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
Tel: +31/(0)10/7043478
Fax: +31/(0)10/7043014
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