generatr

This package is an attempt at an implementation of a "Pythonesque" generator data type and methods. It didn't work out 100% ... there's no magic yield method :( ... but I figured I'd share it anyways, in case anyone might find it useful.

See here for more information on Python generators.

Installation

Install from github with:

# install.packages("devtools")
devtools::install_github("ChrisMuir/generatr")

Example Usage

library(generatr)

Initialize a new generator object with an R vector

gen <- gen_init_with_vector(c(1L, 5L, 20L, 45L))

Check the class of the object gen

class(gen)
#> [1] "integer"     "generator"   "externalptr"

Use gen_next() to get the next value from a generator object, similar to Python's __next__()

for (i in 1:4) {
  print(gen_next(gen))
}
#> [1] 1
#> [1] 5
#> [1] 20
#> [1] 45

Use gen_current() to get the current value from a generator object

gen_current(gen)
#> [1] 45

Once all values have been exhausted, gen_next() will throw a StopIteration error

gen_next(gen)
#> Error in C_gen_next(gen, type_in): StopIteration

We can also initialize a new generator object as an empty object

gen <- gen_init_empty(gen_type = "integer")

Again, check the class of object gen

class(gen)
#> [1] "integer"     "generator"   "externalptr"

New items can be added one by one

for (i in c(1L, 5L, 20L, 45L)) {
  gen_add_element(gen, i)
}

Once we're finished adding items, gen_next() and gen_current() work just like they did in the previous example

for (i in 1:4) {
  print(gen_next(gen))
}
#> [1] 1
#> [1] 5
#> [1] 20
#> [1] 45

Currently, the only data types supported are integer, numeric, character, and logical

gen <- gen_init_with_vector(c("cats", "dogs", "ducks", "frogs", "owls"))
for (i in 1:5) {
  print(gen_next(gen))
}
#> [1] "cats"
#> [1] "dogs"
#> [1] "ducks"
#> [1] "frogs"
#> [1] "owls"