Access elements from an object — at • datastructures

Extracts a set of <key, value> pairs. For hashmaps mappings from $$f: keys -> values,$$ exist so argument which is per default values (since these are going to be retrieved). For bimaps also $$f: values -> keys,$$ mappings exist, such that which can also be keys if the keys from the object should be retrieved.

at(obj, x, which = c("values", "keys"), ...)

# S4 method for bimap,vector,character
at(obj, x, which = c("values", "keys"))

# S4 method for bimap,vector,missing
at(obj, x)

# S4 method for unordered_map,vector,missing
at(obj, x)

Arguments

obj	object to extract values from
x	the set of keys to match the values
which	choose either `values` if the values should get returned
...	other arguments or `keys` if the keys should get returned

Value

returns extracted keys or values from obj

Details

# datastructures: Implementation of core datastructures for R. # # Copyright (C) Simon Dirmeier # # This file is part of datastructures. # # datastructures is free software: you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation, either version 3 of the License, or # (at your option) any later version. # # datastructures is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU General Public License # along with datastructures. If not, see <http://www.gnu.org/licenses/>.

Examples


# access values from a hashmap
h_map <- hashmap("integer")
h_map[seq(2)] <- list(data.frame(a=rexp(3), b=rnorm(3)), environment())
h_map[1L]
#> [[1]]
#>           a           b
#> 1 2.3714437 -1.00599730
#> 2 0.6686661 -0.08433889
#> 3 0.2015218 -0.55406480
#> 

# access values or keys from a bimap
b_map <- bimap("integer", "character")
b_map[seq(5)] <- letters[seq(5)]
at(b_map, c(1L, 3L))
#> [1] "a" "c"
at(b_map, c(1L, 3L), which="values")
#> [1] "a" "c"
at(b_map, c("a", "c"), which="keys")
#> [1] 1 3

# access values from a multimap
m_map <- multimap("integer")
m_map[c(seq(5), seq(5))] <- letters[seq(10)]
at(m_map, 1L)
#> [[1]]
#> [1] "f"
#> 
#> [[2]]
#> [1] "a"
#>