R counting the occurance of similar rows of data frame
- by Matt
I have data in the following format called DF (this is just a made up simplified sample):
eval.num, eval.count, fitness, fitness.mean, green.h.0, green.v.0, offset.0 random
1 1 1500 1500 100 120 40 232342
2 2 1000 1250 100 120 40 11843
3 3 1250 1250 100 120 40 981340234
4 4 1000 1187.5 100 120 40 4363453
5 1 2000 2000 200 100 40 345902
6 1 3000 3000 150 90 10 943
7 1 2000 2000 90 90 100 9304358
8 2 1800 1900 90 90 100 284333
However, the eval.count column is incorrect and I need to fix it. It should report the number of rows with the same values for (green.h.0, green.v.0, and offset.0) by only looking at the previous rows.
The example above uses the expected values, but assume they are incorrect.
How can I add a new column (say "count") which will count all previous rows which have the same values of the specified variables?
I have gotten help on a similar problem of just selecting all rows with the same values for specified columns, so I supposed I could just write a loop around that, but it seems inefficient to me.
