I'm running into a problem I can't seem to find a solution for. I'm
attempting to add sequences into an existing data set based on subsets
of the data. I've done this using a for loop with a small subset of
data, but attempting the same process using real data (200k rows) is
taking way too long.
Here is some sample data and my ultimate goal
> row1<-c(0,1,2,3,4,5,1,2,3,4)
> row2<-c(1,1,1,1,1,1,2,2,2,2)
> stuff<-data.frame(row1=row1,row2=row2)
> stuff
row1 row2
1 0 1
2 1 1
3 2 1
4 3 1
5 4 1
6 5 1
7 1 2
8 2 2
9 3 2
10 4 2
I need to derive 2 columns. I need a sequence for each unique row2, and
then I need a sequence that restarts based on a cutoff value for row1
and unique row2. The following table is what is -should- look like using
a cutoff of 3 for row4
row1 row2 row3 row4
1 0 1 1 1
2 1 1 2 2
3 2 1 3 3
4 3 1 4 1
5 4 1 5 2
6 5 1 6 3
7 1 2 1 1
8 2 2 2 2
9 3 2 3 1
10 4 2 4 2
I need something like row3<-sequence(nrow(unique(stuff$row2))) that
actually works :-) Here is the for loop that functions properly for
row3:
stuff$row3<-c(1)
for (i in 2:nrow(stuff)) { if ( stuff$row2[i] == stuff$row2[i-1]) {
stuff$row3[i] = stuff$row3[i-1]+1}}
Thanks!
Jason Baucom
Ateb, Inc.
919.882.4992 O
919.872.1645 F
www.ateb.com <http://www.ateb.com/>
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