I've just tried to merge 2 data sets thinking they would only keep the common columns, but noticed the column count was not adding up. I've then replicated a simple example and got the same thing happening.
q1. why doesn't 'b' have a column name? q2. when I merge, why does the new column 'y' have all values as 5.1? Thanks in advance, Mr. confused > a <- iris[,] > b <- iris[,1] > > head(a) Sepal.Length Sepal.Width Petal.Length Petal.Width Species 1 5.1 3.5 1.4 0.2 setosa 2 4.9 3.0 1.4 0.2 setosa 3 4.7 3.2 1.3 0.2 setosa 4 4.6 3.1 1.5 0.2 setosa 5 5.0 3.6 1.4 0.2 setosa 6 5.4 3.9 1.7 0.4 setosa > head(b) [1] 5.1 4.9 4.7 4.6 5.0 5.4 > > c <-merge(a,b) > head(c) Sepal.Length Sepal.Width Petal.Length Petal.Width Species y 1 5.1 3.5 1.4 0.2 setosa 5.1 2 4.9 3.0 1.4 0.2 setosa 5.1 3 4.7 3.2 1.3 0.2 setosa 5.1 4 4.6 3.1 1.5 0.2 setosa 5.1 5 5.0 3.6 1.4 0.2 setosa 5.1 6 5.4 3.9 1.7 0.4 setosa 5.1 > > NCOL(a) [1] 5 > NCOL(b) [1] 1 > NCOL(c) [1] 6 > -- View this message in context: http://r.789695.n4.nabble.com/where-did-the-column-names-go-to-tp2306267p2306267.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.