Remove an element of a list by name

Question

I'm working with a long named list and I'm trying to keep/remove elements that match a certain name, within a tidyverse context, similar to

dplyr::select(contains("pattern"))

However, I'm having issues figuring it out.

library(tidyverse)

a_list <- 
  list(a = "asdfg",
       b = "qwerty",
       c = "zxcvb")

a_list %>% pluck("a") # works
a_list %>% pluck(contains("a")) #does not work

a_list[2:3] # this is what I want
a_list %>% pluck(-"a") # but this does not work

Answer 1

To remove by name you could use:

a_list %>% purrr::list_modify("a" = NULL)
$`b`
[1] "qwerty"

$c
[1] "zxcvb"

I'm not sure the other answers are using the name of the element, rather than the element itself for selection. The example you gave is slightly confusing since the element 'a' both contains 'a' in it's value AND is called 'a'. So it's easy to get mixed up. To show the difference I'll modify the example slightly.

b_list <- 
  list(a = "bsdfg",
       b = "awerty",
       c = "zxcvb")

b_list %>% purrr::list_modify("a" = NULL)

returns

$`b`
[1] "awerty"

$c
[1] "zxcvb"

but

purrr::discard(b_list,.p = ~stringr::str_detect(.x,"a"))

returns

$`a`
[1] "bsdfg"

$c
[1] "zxcvb"