Tidyverse selections implement a dialect of R where operators make it easy to select variables:
: for selecting a range of consecutive variables.
! for taking the complement of a set of variables.
& and | for selecting the intersection or the union of two sets of variables.
c() for combining selections.
In addition, you can use selection helpers such as:
everything(): Matches all variables.
last_col(): Select last variable, possibly with an offset.
These helpers select variables based on their names:
starts_with(): Starts with a prefix.
ends_with(): Ends with a suffix.
contains(): Contains a literal string.
matches(): Matches a regular expression.
num_range(): Matches a numerical range like x01, x02, x03.
These functions select variables from a character vector.
all_of(): Matches variable names in a character vector. All names must be present, otherwise an out-of-bounds error is thrown.
any_of(): Same as all_of(), except that no error is thrown for names that don’t exist.
select使用變量作爲參數的時候會警告，select(var_vector)的正確寫法應該是select(all_of(var_vector))，因爲可能出現 var_vector這個變量名本身是column name的情況。