Confusion matrix proportions

[jxu]

It would be nice to have a flag to compute proportions out of total instead of counts.

conf_mat object is not a matrix, so I can't do something like conf_mat(data, truth, pred) / nrow(data), but I can do it by passing it to tidy.
Is there a simple function to turn conf_mat object into plain matrix or tibble, keeping the 2x2 layout?