`dfr as-date` for dataframe

Converts string to date.

Signature

> dfr as-date (format) --not-exact

format: formatting date string
--not-exact (-n): the format string may be contained in the date (e.g. foo-2021-01-01-bar could match 2021-01-01)

input	output
any	any

Converts string to date

> ["2021-12-30" "2021-12-31"] | dfr into-df | dfr as-datetime "%Y-%m-%d"

Format example: "%Y-%m-%d" => 2021-12-31 "%d-%m-%Y" => 31-12-2021 "%Y%m%d" => 2021319 (2021-03-19)

Tips: Dataframe commands were not shipped in the official binaries by default, you have to build it with --features=dataframe flag