data.table aware

[rsaporta]

Making skimr data.table aware

Summary

1. include key in output
2. no pesky warnings when dtplyr is loaded (closes #621 )

Details:

1. include key in output

• if data is a data.table summary_df will include the key, defaulting to NULL if no key is set (this latter part matches the output of data.table::key(data)
• if data is not a data.table, there is no change to summary_df
• if data was a data.table and converted to either data.frame or tibble, then behavior of skimr is unchanged. (several test outputs added to confirm)

2. no pesky warnings when dtplyr is loaded

• The warnings are a function of standard dplyr/dtplyr behavior.
• Resolved by creating skim_by_type.data.table

tests:

• Several sample outputs and tests created

[elinw]

Thank you for this, I think it makes a lot of sense for us to support data.table cleanly.

[elinw]

@rsaporta Are you able to do the requested changes? Also you can add yourself as a contributor in the DESCRIPTION file.

[elinw]

Do we really need to export dt_key()?

[elinw]

@rsaporta Are you able to update your branch? Or would you rather have us take care of it?

[elinw]

I'm closing this in favor of https://github.com/ropensci/skimr/pull/633 ... I'm still not sure if we need the @export.