Extended column specifications are used in the read_interlaced_*() family
of functions in the col_types argument to specify the value and missing
reason channel types.
Usage
x_cols(..., .default = v_col_guess())
x_cols_only(...)Details
Like readr::cols(), x_cols() includes all the columns in the input data,
guessing the column types as the default, and creating missing reason
channels according to the na = argument in the read function.
x_cols_only() only includes the columns you specify, like
readr::cols_only(). In general, you can substitute list() for x_cols()
without changing the behavior.
