Dictionary {mlr3misc}

Key-Value Storage

Description

A key-value store for R6::R6 objects. On retrieval of an object, the following applies:

• If the object is a R6ClassGenerator, it is initialized with new().

• If the object is a function, it is called and must return an instance of a R6::R6 object.

• If the object is an instance of a R6 class, it is returned as-is.

Default argument required for construction can be stored alongside their constructors by passing them to ⁠$add()⁠.

S3 methods

• as.data.table(d)
  Dictionary -> data.table::data.table()
  Converts the dictionary to a data.table::data.table().

Public fields

items

(environment())
Stores the items of the dictionary

Methods

Public methods

• Dictionary$new()

• Dictionary$format()

• Dictionary$print()

• Dictionary$keys()

• Dictionary$has()

• Dictionary$get()

• Dictionary$mget()

• Dictionary$add()

• Dictionary$remove()

• Dictionary$prototype_args()

• Dictionary$clone()

Method new()

Construct a new Dictionary.

Usage

Dictionary$new()

Method format()

Format object as simple string.

Usage

Dictionary$format(...)

Arguments

...

(ignored).

Method print()

Print object.

Usage

Dictionary$print()

Method keys()

Returns all keys which comply to the regular expression pattern. If pattern is NULL (default), all keys are returned.

Usage

Dictionary$keys(pattern = NULL)

Arguments

pattern

(character(1)).

Returns

character() of keys.

Method has()

Returns a logical vector with TRUE at its i-th position if the i-th key exists.

Usage

Dictionary$has(keys)

Arguments

keys

(character()).

Returns

logical().

Method get()

Retrieves object with key key from the dictionary. Additional arguments must be named and are passed to the constructor of the stored object.

Usage

Dictionary$get(key, ..., .prototype = FALSE)

Arguments

key

(character(1)).

...

(any)
Passed down to constructor.

.prototype

(logical(1))
Whether to construct a prototype object.

Returns

Object with corresponding key.

Method mget()

Returns objects with keys keys in a list named with keys. Additional arguments must be named and are passed to the constructors of the stored objects.

Usage

Dictionary$mget(keys, ...)

Arguments

keys

(character()).

...

(any)
Passed down to constructor.

Returns

Named list() of objects with corresponding keys.

Method add()

Adds object value to the dictionary with key key, potentially overwriting a previously stored item. Additional arguments in ... must be named and are passed as default arguments to value during construction.

Usage

Dictionary$add(key, value, ..., .prototype_args = list())

Arguments

key

(character(1)).

value

(any).

...

(any)
Passed down to constructor.

.prototype_args

(list())
List of arguments to construct a prototype object. Can be used when objects have construction arguments without defaults.

Returns

Dictionary.

Method remove()

Removes objects with from the dictionary.

Usage

Dictionary$remove(keys)

Arguments

keys

(character())
Keys of objects to remove.

Returns

Dictionary.

Method prototype_args()

Returns the arguments required to construct a simple prototype of the object.

Usage

Dictionary$prototype_args(key)

Arguments

key

(character(1))
Key of object to query for required arguments.

Returns

list() of prototype arguments

Method clone()

The objects of this class are cloneable with this method.

Usage

Dictionary$clone(deep = FALSE)

Arguments

deep

Whether to make a deep clone.

Examples

library(R6)
item1 = R6Class("Item", public = list(x = 1))
item2 = R6Class("Item", public = list(x = 2))
d = Dictionary$new()
d$add("a", item1)
d$add("b", item2)
d$add("c", item1$new())
d$keys()
d$get("a")
d$mget(c("a", "b"))