r - How can I use merge to cbind two dataframes

Question

Suppose I have two dataframes:

df1 <- data.frame(matrix(rnorm(10*10),ncol=10))
df2 <- data.frame(matrix(rnorm(10*10),ncol=10))
colnames(df1) <- 1:10
colnames(df2) <- 11:20

How do I use merge to cbind these (I already know about cbind but I am interested in the application of merge here).

Answer 1

There's nothing here on which to merge other than row names.

merge(df1, df2, by=0)

Note the order of the rows in the result! These are lexicaly sorted by row name. To get the proper order, use order:

x <- merge(df1, df2, by=0)
x[order(as.numeric(x$Row.names)),]