[R] removing fields of the same group from a data frame
Dear all, I'm trying to find a a way to remove certain fields belonging to the same group from a data frame structure. I have a data frame like this: foo v1 v2 v3 1 1 a 6 2 a 3 8 a 4 4 b 4 4 b 2 1 c 1 6 d Each row can then be grouped according to the third column: a, b, c, d. Then I would like to remove all fields that belong to a group with less than X members, for example less than 3 members, then the resulting data frame structure would look like: foo v1 v2 v3 1 1 a 6 2 a 3 8 a Is there some simple way to do this in R? Thanks in advance. /Oscar [[alternative HTML version deleted]] __ 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.
Re: [R] removing fields of the same group from a data frame
Try this: subset(foo, v3 %in% names(which(!table(foo$v3) 3))) On Wed, Mar 24, 2010 at 10:38 AM, Oscar Franzén oscar.franz...@gmail.com wrote: Dear all, I'm trying to find a a way to remove certain fields belonging to the same group from a data frame structure. I have a data frame like this: foo v1 v2 v3 1 1 a 6 2 a 3 8 a 4 4 b 4 4 b 2 1 c 1 6 d Each row can then be grouped according to the third column: a, b, c, d. Then I would like to remove all fields that belong to a group with less than X members, for example less than 3 members, then the resulting data frame structure would look like: foo v1 v2 v3 1 1 a 6 2 a 3 8 a Is there some simple way to do this in R? Thanks in advance. /Oscar [[alternative HTML version deleted]] __ 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. -- Henrique Dallazuanna Curitiba-Paraná-Brasil 25° 25' 40 S 49° 16' 22 O __ 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.
Re: [R] removing fields of the same group from a data frame
On Mar 24, 2010, at 8:38 AM, Oscar Franzén wrote: Dear all, I'm trying to find a a way to remove certain fields belonging to the same group from a data frame structure. I have a data frame like this: foo v1 v2 v3 1 1 a 6 2 a 3 8 a 4 4 b 4 4 b 2 1 c 1 6 d Each row can then be grouped according to the third column: a, b, c, d. Then I would like to remove all fields that belong to a group with less than X members, for example less than 3 members, then the resulting data frame structure would look like: foo v1 v2 v3 1 1 a 6 2 a 3 8 a Is there some simple way to do this in R? Thanks in advance. /Oscar DF v1 v2 v3 1 1 1 a 2 6 2 a 3 3 8 a 4 4 4 b 5 4 4 b 6 2 1 c 7 1 6 d subset(DF, !v3 %in% names(which(table(v3) 3))) v1 v2 v3 1 1 1 a 2 6 2 a 3 3 8 a The use of table() gets us: table(DF$v3) 3 a b c d FALSE TRUE TRUE TRUE followed by: names(which(table(DF$v3) 3)) [1] b c d which gives us the values of v3 that don't have at least 3 entries. When using subset(), the variables are evaluated first within the data frame, hence we can drop the 'DF$' in the function call. The use of %in% in subset() allows us to include or exclude certain values from a set comparison. We could also reverse the logic, yielding the same result: subset(DF, v3 %in% names(which(table(v3) = 3))) v1 v2 v3 1 1 1 a 2 6 2 a 3 3 8 a See ?table, ?subset and ?%in% for more information. HTH, Marc Schwartz __ 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.
