Generic support for dimension-aware attributes, e.g. colattr(x, 'gender')

[HenrikBengtsson]

Description

Generic support for dimension-aware attributes that are acknowledged whenever the object is subsetted. For vectors we have names(), for matrices and data frames we have rownames() and colnames(), and for arrays and other objects we have dimnames().

Example

> x <- matrix(1:12, ncol=4)
> colnames(x) <- c("A", "B", "C", "D")
> colattr(x, 'gender') <- c("male", "male", "female", "male")
> colattr(x, 'age') <- c(26, 43, 28, 33)
> x

     male male female male
       26   43     28   33
        A    B      C    D
[1,]    1    4      7   10
[2,]    2    5      8   11
[3,]    3    6      9   12

> y <- x[,2:3]
> y
     male female
       43     28
        B      C
[1,]    4      7
[2,]    5      8
[3,]    6      9

> colnames(y)
[1] B C
> colattr(y, 'name')
[1] B C
> colattr(y, 'gender')
[1] "male" "female"
> colattr(y, 'age')
[1] 43 28

[HenrikBengtsson]

ML commented (2015-11-14):

This is essentially Biobase::AnnotatedDataFrame and S4Vectors::DataFrame. One interesting direction would be to consider the meta columns as grouping factors and use them to implement pivot-table functionality.

[karoliskoncevicius]

I have an alternative package that tries to address this issue for matrices: annmatrix. AnnotatedDataFrame and BioConductor objects in general were a bit too heavy for my taste, so I tried to construct a matrix-based custom S3 object. It seems to work quite well, better than I initially imagined. One major upside is that the object is still a proper matrix and can be passed to functions expecting a matrix.