cbind {base}R Documentation

Combine R Objects by Rows or Columns

Description

Take a sequence of vector, matrix or data frames arguments and combine by columns or rows, respectively. There may be methods for other R classes.

Usage

cbind(...)
rbind(...)

Details

The functions cbind and rbind are generic, with methods for data frames. The data frame method will be used if an argument is a data frame and the rest are vectors or matrices. There can be other methods, for example cbind.ts in package ts.

If there are several matrix arguments, they must all have the same number of columns (or rows) and this will be the number of columns (or rows) of the result. If all the arguments are vectors, the number of columns (rows) in the result is equal to the length of the longest vector. Values in shorter arguments are recycled to achieve this length (with a warning when they are recycled only fractionally).

When the arguments consist of a mix of matrices and vectors the number of columns (rows) of the result is determined by the number of columns (rows) of the matrix arguments. Any vectors have their values recycled or subsetted to achieve this length.

Note

The method dispatching is not done via UseMethod(..), but by C-internal dispatching. Therefore, there's no need for, e.g., rbind.default.

The dispatch algorithm is described in the source file (`.../src/main/bind.c') as

  1. For each argument we get the list of possible class memberships from the class attribute.

  2. We inspect each class in turn to see if there is an an applicable method.

  3. If we find an applicable method we make sure that it is identical to any method determined for prior arguments. If it is identical, we proceed, otherwise we immediately drop through to the default code.
If you want to combine other objects with data frames, it may be necessary to coerce them to data frames first.

See Also

c to combine vectors (and lists) as vectors, data.frame to combine vectors and matrices as a data frame.

Examples

cbind(1, 1:7) # the '1' (= shorter vector) is recycled
cbind(1:7, diag(3))# vector is subset -> warning

cbind(0, rbind(1, 1:3))

cbind(0, matrix(1, nrow=0, ncol=4))#> Warning (making sense)
dim(cbind(0, matrix(1, nrow=2, ncol=0)))#-> 2 x 1
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