check the usage of as.vector

[elong0527]

From CRAN maintainer

Dear maintainers,

This concerns the CRAN packages

Note that your package have started failing their checks with the latest development versions of R, 'R-devel' for short.

The reason is that we/I have introduced a new
as.vector.data.frame() method, and saying in NEWS

    • as.vector() gains a data.frame method which returns a
      simple named list, also obeying a long standing      
      ‘FIXME’ to enable as.vector(<data.frame>, mode="list").
      This will break code relying on 'as.vector(<data.frame>)' to
      return the unchanged data frame.

The last sentence applies to your respective packages where you call as.vector()  on a data frame -- which in R <= 4.1.x returns the data frame *unchanged* howeve now (in R-devel) returns a list (with the data frame
columns) but not a data frame anymore.
That's why your code now fails.
The solution will be to simply *NOT* call  as.vector(.) in that part of the code ..

Please let me/us know if you need help fixing your respective
package(s) to work flawlessly on the latest version of R, R-devel.
Note that this change will also make your code very slightly faster:
you should never have called as.vector(.) on a data frame: it does not do anything (but cost a few nanoseconds ..).