Suppose you have a large df and you want a simple and fast way to get df1 from df (a large R dataframe):
df:
index var1 var2 var3 var4
0 2 4 8 7
1 2 3 9 6
2 1 5 10 8
2 1 5 7 8
2 2 9 33 10
2 2 9 17 10
3 3 6 6 9
3 4 7 11 10
and the idea is to aggregate (by sum) the rows with the same index and the same var1 without changing the others. Notice that var4 is the same per index var2 combination.
df1:
index var1 var2 var3 var4
0 2 4 8 7
1 2 3 9 6
2 1 5 17 8
2 2 9 50 10
3 3 6 6 9
3 4 7 11 10
Maybe you can use aggregate() as below
v <- aggregate(df[-(1:2)], df[1:2], function(x) sum(unique(x)))
res <- v[order(v$index),]
and thus
> res
index var1 var2 var3 var4
2 0 2 4 8 7
3 1 2 3 9 6
1 2 1 5 17 8
4 2 2 9 50 10
5 3 3 6 6 9
6 3 4 7 11 10