I am an R beginner looking to add a new variable to a long dataset. I currently have a long dataset with three variables--ID; latitude; longitude. I'd like to add a fourth variable that identifies the location within each group. There are a different number of locations within each group.
For example, this is what my data currently look like:
ID lat lon
100 33.737 -84.433
100 33.751 -84.486
101 33.681 -84.402
102 33.756 -84.414
102 33.751 -84.486
102 33.730 -84.446
103 33.751 -84.486
103 33.724 -84.499
104 33.737 -84.433
104 33.799 -84.195
105 33.678 -84.417
105 33.661 -84.448
106 33.728 -84.508
107 33.852 -84.359
107 33.756 -84.414
107 33.737 -84.433
And here is what I would like the data to look like:
ID lat lon location_number
100 33.737 -84.433 1
100 33.751 -84.486 2
101 33.681 -84.402 1
102 33.756 -84.414 1
102 33.751 -84.486 2
102 33.730 -84.446 3
103 33.751 -84.486 1
103 33.724 -84.499 2
104 33.737 -84.433 1
104 33.799 -84.195 2
105 33.678 -84.417 1
105 33.661 -84.448 2
106 33.728 -84.508 1
107 33.852 -84.359 1
107 33.756 -84.414 2
107 33.737 -84.433 3
Thank you so much for any assistance you are able to provide!
