# col

##### Column Indexes

Returns a matrix of integers indicating their column number in a matrix-like object, or a factor of column labels.

- Keywords
- array

##### Usage

```
col(x, as.factor = FALSE)
.col(dim)
```

##### Arguments

- x
a matrix-like object, that is one with a two-dimensional

`dim`

.- dim
a matrix dimension, i.e., an integer valued numeric vector of length two (with non-negative entries).

- as.factor
a logical value indicating whether the value should be returned as a factor of column labels (created if necessary) rather than as numbers.

##### Value

An integer (or factor) matrix with the same dimensions as `x`

and whose
`ij`

-th element is equal to `j`

(or the `j`

-th column label).

##### References

Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988)
*The New S Language*.
Wadsworth & Brooks/Cole.

##### See Also

`row`

to get rows;
`slice.index`

for a general way to get slice indices
in an array.

##### Examples

`library(base)`

```
# NOT RUN {
# extract an off-diagonal of a matrix
ma <- matrix(1:12, 3, 4)
ma[row(ma) == col(ma) + 1]
# create an identity 5-by-5 matrix more slowly than diag(n = 5):
x <- matrix(0, nrow = 5, ncol = 5)
x[row(x) == col(x)] <- 1
(i34 <- .col(3:4))
stopifnot(identical(i34, .col(c(3,4)))) # 'dim' maybe "double"
# }
```

*Documentation reproduced from package base, version 3.6.0, License: Part of R 3.6.0*

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