Hi, I'm new to R and new to this forum. I'm struggling with trying to extract certain rows of data from my data.frame. The data.frame has eleven columns. Among those columns are "FISH_ID" and "DATE_TIME". FISH_ID is a factor. For each of my 21 unique FISH_IDs (levels) I have a few to a few thousand rows, each row with a unique DATE_TIME value. I would like to obtain, for each FISH_ID, the entire record from the data.frame with the latest DATE_TIME value (i.e. max (DATE_TIME). Thus, the resulting subset would be the original eleven columns by 21 rows (one for each level of my FISH_ID).
Any advice would be greatly appreciated. Nick -- View this message in context: http://n4.nabble.com/How-can-I-return-rows-from-a-data-frame-with-maximum-value-by-factor-tp1596777p1596777.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
