On 2011-04-23 07:02, David Winsemius wrote:
On Apr 23, 2011, at 9:05 AM, - - wrote:I have a table. First column is a date, second column is an index and other columns contains some other values. I want to remove, for each date, the row with the smallest index (it is not necessarily 1). ex: in the following table, I want to remove row 1 (2013-05-12 with index 2) and row 8 (2013-05-13 with index 1) day index values 1 2013-05-12 2 xxxx 2 2013-05-12 3 xxxx 3 2013-05-12 4 xxxx 4 2013-05-12 5 xxxx 5 2013-05-12 6 xxxx 6 2013-05-12 7 xxxx 7 2013-05-12 8 xxxx 8 2013-05-13 1 xxxx 9 2013-05-13 3 xxxx 10 2013-05-13 4 xxxx 11 2013-05-13 5 xxxx 12 2013-05-13 6 xxxx 13 2013-05-13 7 xxxx 14 2013-05-13 8 xxxx 15 2013-05-13 9 xxxx 16 2013-05-13 10 xxxx 17 2013-05-13 12 xxxxConsider using ave and creating a logical vector that you then negate: > ave(dat$index, list(dat$day), FUN=function(x) x==min(x)) [1] 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 dat[ -ave(dat$index, list(dat$day), FUN=function(x) x==min(x)), ]
ave() is one of those really handy functions, but I think that you meant dat[ !ave(dat$index, list(dat$day), FUN=function(x) x==min(x)), ] Here's another way, using the plyr package require(plyr) ddply(dat, .(day), .fun = function(x) subset(x, index != min(index))) Peter Ehlers
-- David Winsemius, MD West Hartford, CT ______________________________________________ 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.
______________________________________________ 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.
