I have a data frame final which looks like this
TrackIndex Time x_position y_position
1 1 0.1034 425 171
2 1 0.1379 425 169
3 1 0.1724 427 166
.........
125 25 1.1030 462 397
126 25 1.1380 462 397
127 25 1.1720 462 397
128 25 1.2070 462 397
129 25 1.2410 461 398
130 25 1.2760 462 399
131 25 1.3100 461 399
132 25 1.3450 461 399
133 25 1.3790 460 399
134 25 1.4140 460 399
.....
268 41 1.8280 302 280
269 41 1.8620 303 279
270 41 1.8970 302 280
271 41 1.9310 302 280
272 41 1.9660 302 281
273 41 2.0000 302 281
274 41 2.0340 302 281
275 41 2.0690 302 282
276 41 2.1030 302 282
277 41 2.1380 302 282
278 41 2.1720 302 283
........
I sorted this data frame by factor "TrackIndex", and selected only the first 5 rows for each unique TrackIndex using "by" function.
finalbyfactor<-by(data = final, INDICES = final$TrackIndex, FUN = function(x) head(x, 5))
This gave me the following results
> finalbyfactor
final$TrackIndex: 1
TrackIndex Time x_position y_position
1 1 0.1034 425 171
2 1 0.1379 425 169
3 1 0.1724 427 166
4 1 0.2069 427 167
5 1 0.2414 427 167
-----------------------------------------------------------------------------
final$TrackIndex: 25
TrackIndex Time x_position y_position
125 25 1.103 462 397
126 25 1.138 462 397
127 25 1.172 462 397
128 25 1.207 462 397
129 25 1.241 461 398
-----------------------------------------------------------------------------
final$TrackIndex: 41
TrackIndex Time x_position y_position
268 41 1.828 302 280
269 41 1.862 303 279
270 41 1.897 302 280
271 41 1.931 302 280
272 41 1.966 302 281
Now I want to recombine the selected rows into one data frame as the initial one. How can I do it? I tried rbind and merge, both did not work.
