Join method for epi_df

[JavierMtzRdz]

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Join method for epi_df

Here's how *_join.epi_df performs across different scenarios:

• When keys are unique and valid, the output remains an epi_df:
  • Joining two epi_df objects with different keys correctly updates the combined other_keys metadata.
  • The original grouping structure of the input epi_df is preserved.
  • When *_type internal attributes do not match, it issues a warning.
• The output converts to a standard tibble if:
  • The join results in multiple rows for the same key combination. This includes cases where two epi_df objects are not joined by geo_value or time_value.
  • A key column is missing from the result. A warning is issued.
  • The join introduces NA values into key columns. A warning is issued suggesting the use of inner_join.
  • cross_join() is used.

I also added an internal force_meta to easily adjust geo_type and time_type when using a pipe, as shown in the example below.

week <- tibble::tibble(geo_value = "ca", time_value = as.Date("2020-01-01"), val2 = 2) %>%
    as_epi_df() %>%
    epiprocess:::force_meta(time_type = "week")

Magic GitHub syntax to mark associated Issue(s) as resolved when this is merged into the default branch

• Partially fixes epi_df joins to data frames with richer keys yields invalid epi_df #671

[brookslogan]

todo: anyMissing is sort of deprecated; replace with vctrs::vec_any_missing or anyNA; vctrs one is a bit more general, which might make it easier to generalize the types we accept for geo & time values later.