dict: Python-style Dictionaries in R
In kevinushey/Kmisc: Kevin Miscellaneous

Description Usage Arguments Details Warning Examples

Dictionaries, i.e., hashed key-value pairs, are implemented in R using environments as a backend.

1	dict(..., `_size` = 29L)

`...`	Named arguments used in constructing the dictionary.
`'_size'`	The number of 'buckets' used. This is the maximum of `29L` and the number of named arguments passed to `...`.

Dictionaries are just hashed R environments with emptyenv() as a parent.

Dictionaries have reference semantics, so modifying a dictionary within a function will modify the dictionary passed in, not a copy! Use the copy function to duplicate a dict.

## Reference semantics -- be careful!
x <- dict()
y <- x
x[["a"]] <- 100
print(y[["a"]])

## Use copy to be explicit
y <- copy(x)
x[["b"]] <- 200
try(y[["b"]], silent = TRUE)

## Named lookup can be much faster in a dictionary
x <- as.list(1:1E5)
names(x) <- paste0("Element_", 1:1E5)
dict <- as.dict(x)
if (require(microbenchmark)) {
  microbenchmark(
    x[["Element_1"]],
    dict[["Element_1"]],
    x[["Element_1000"]],
    dict[["Element_1000"]],
    x[["Element_100000"]],
    dict[["Element_100000"]]
  )
}