R语言 dplyr selec 辅助函数
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
使用变量作为参数的时候会警告,select(var_vector)
的正确写法应该是select(all_of(var_vector))
,因为可能出现 var_vector
这个变量名本身是column name的情况。