Inserting column in between -- "better" way?

Actually Sara's method fails if the insertion is after the first or before
the last column:

x <- data.frame(A=1:3, B=1:3, C=1:3, D=1:3, E=1:3)
newcol <- 4:6
cbind(x[,1], newcol, x[,2:ncol(x)])

Sarah (sic) is on the right track, just lose the commas so that you don't drop to a vector:

x <- data.frame(A=1:3, B=1:3, C=1:3, D=1:3, E=1:3)
newcol <- 4:6
cbind(x[1], newcol, x[2:ncol(x)])

A newcol B C D E
1 1      4 1 1 1 1
2 2      5 2 2 2 2
3 3      6 3 3 3 3

Also notice that there is a named form of cbind

cbind(x[1], foo=4:6, x[2:ncol(x)])

A foo B C D E
1 1   4 1 1 1 1
2 2   5 2 2 2 2
3 3   6 3 3 3 3


and that things will work (mostly) with matrices and data frames too:

newcol <- data.frame(x=4:6,y=6:4)
cbind(x[1], newcol, x[2:ncol(x)])

A x y B C D E
1 1 4 6 1 1 1 1
2 2 5 5 2 2 2 2
3 3 6 4 3 3 3 3

cbind(x[1], as.matrix(newcol), x[2:ncol(x)])

A x y B C D E
1 1 4 6 1 1 1 1
2 2 5 5 2 2 2 2
3 3 6 4 3 3 3 3

(The "mostly" bit refers to some slight oddness occurring if you cbind a matrix with no column names:

cbind(x[1], cbind(4:6,7:9), x[2:ncol(x)])

A 1 2 B C D E
1 1 4 7 1 1 1 1
2 2 5 8 2 2 2 2
3 3 6 9 3 3 3 3

)

Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com
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