Provide an option to avoid format guesser

[robertzk]

Maybe we could give all the parsing functions that rely on the guesser an additional option to use a full scan, with the user knowing it will impact performance? This will avoid issues like #307

[vspinu]

👍

• Add train option to parse_date_time and make no-training the default.
• Ignore training option when only one order has been supplied.

[peterhurford]

👍

[vspinu]

I am afraid it's not possible to avoid sparse guesser because of the flexibility of the "orders" versus the sprtime "formats". When you supply ymd it can match "12-12-12" or "2012-12-12" or "121212" etc. You cannot solve that without training. So I am afraid you just have to use alternative functions (sptrtime, fast_sptrtime or parse_date_time2) that don't perform guessing.

I have now documented this in the parse_date_time documentation.

[vspinu]

I came back on this one. There is now an option exact=TRUE that treats orders as strptime formats and doesn't perform any training or guessing.

[peterhurford]

👍 Awesome!

[vspinu]

In next version parse_date_time gained train=TRUE and drop=FALSE arguments. As you could guess, formats are no longer dropped. Similar issues should not occur anymore.