Ordered data in create_table()

[jesse-smith]

create_table() now attempts to order the input appropriately when coercing to factor. This seems to be working-ish, but there's a new issue of implicitly missing values in things like time. Type-stability of the output is starting to seem like more of a bug than a feature. To summarize:

• Factors are currently always returned by create_table(). This allows us to nicely control plotting order in the plot_* functions.

• Some information is lost when coercing to factors. This can be mitigating in principle but requires significant work to re-implement existing defaults (i.e. date plotting in ggplot2)

• We want to maintain sensible plotting for factor-type data, but also use the defaults for non-factor-type data

[jesse-smith]

First thoughts:

1. Given that the issue is a plotting problem, this should really be a discussion on the plot_* family, which means I've probably implemented type coercion in the wrong function (the plot_* family should probably do it, rather that the create_* family).

2. The primary advantage of factors in plotting is that we can control ordering with levels. This makes sense for reordering categories based on frequency; less sense for others.

Potential fix

Move factor coercion to the plot_* family as a helper function. Add an infreq argument to that family and only use the helper when infreq = TRUE.

This will require a good bit of time to refactor.

[jesse-smith]

Actually, adding infreq will only be a switch to call the helper (or not). Since we're composing with pipes, it may be clearer to create a separate function that transforms the output of create_table() to a factor. This can then be passed to the plot_* family as usual. Benefits from chunking the conversion behavior separately from the plotting behavior.