[R] don't print object attributes

[Duncan Murdoch]

On 28/08/2012 2:16 PM, Liviu Andronic wrote:
> On Tue, Aug 28, 2012 at 7:34 PM, Duncan Murdoch
> <murdoch.duncan at gmail.com> wrote:
> > Assign a class to the object, and write a print method for it.
> >
> > For example, this doesn't quite do what you want, but it's a start:
> >
> > print.noattributes <- function(x, ...) {
> >    attributes(x) <- NULL
> >    print(x)
> > }
> >
> > class(x) <- "noattributes"
> > x
> >
> > It loses some attributes that you probably want to keep (e.g. the names),
> > but otherwise works on your example.
> >
> I've already tried this solution but that's exactly the trouble with
> this approach. Do this on a data.frame and loses important
> information.
>
> I came up with a modified version of the above:
> print_noattr <- function(x, keep.some=T, ...){
>      if(keep.some) xa <- attributes(x)[c('names', 'row.names', 'class')]
>      attributes(x) <- NULL
>      if(keep.some) attributes(x) <- xa
>      print(x)
> }
>
> > x <- dlply(iris, .(Species), function(x) describe(x[, 'Sepal.Length']))
> > print_noattr(x)
> $setosa
> x[, "Sepal.Length"]
>        n missing  unique    Mean     .05     .10     .25     .50     .75
>       50       0      15   5.006    4.40    4.59    4.80    5.00    5.20
>      .90     .95
>     5.41    5.61
>
>            4.3 4.4 4.5 4.6 4.7 4.8 4.9  5 5.1 5.2 5.3 5.4 5.5 5.7 5.8
> Frequency   1   3   1   4   2   5   4  8   8   3   1   5   2   2   1
> %           2   6   2   8   4  10   8 16  16   6   2  10   4   4   2
>
> $versicolor
> x[, "Sepal.Length"]
>        n missing  unique    Mean     .05     .10     .25     .50     .75
>       50       0      21   5.936   5.045   5.380   5.600   5.900   6.300
>      .90     .95
>    6.700   6.755
>
> lowest : 4.9 5.0 5.1 5.2 5.4, highest: 6.6 6.7 6.8 6.9 7.0
>
> $virginica
> x[, "Sepal.Length"]
>        n missing  unique    Mean     .05     .10     .25     .50     .75
>       50       0      21   6.588   5.745   5.800   6.225   6.500   6.900
>      .90     .95
>    7.610   7.700
>
> lowest : 4.9 5.6 5.7 5.8 5.9, highest: 7.3 7.4 7.6 7.7 7.9
>
>
> However this still feels like a hack, and the function should be
> modified if the object in question contains some other crucial
> attributes.

I think it's reasonable to say it feels like a hack, because it is. x 
should have had a class and a print method for that class in the first 
place, if the attributes are not something that users should see.  If 
they are things you should see, then suppressing them is a bad idea.

Duncan Murdoch

>
>
>
> On Tue, Aug 28, 2012 at 7:44 PM, Peter Ehlers <ehlers at ucalgary.ca> wrote:
> > It seems that class "listof" also works:
> >
> >   class(x) <- "listof"
> >   x
> >
> This works great. Thanks.
>
> Liviu