@wbg-mde/r-script v1.0.5

r-script

A simple little module for passing data from NodeJS to R (and back again).

Data passed from node is converted into a list and loaded into the R environment as the variable input. No special syntax in R is needed. For better portability/reliability, it's recommended to load packages with needs (comes packaged inside the module — no installation required).

Installation

npm install r-script

Example

var R = require("r-script");

Synchronous

// example.js

var out = R("ex-sync.R")
  .data("hello world", 20)
  .callSync();
  
console.log(out);

// [ 'oedorlwlh l', 'oldlrhelwo ', 'erllol dhow', ' lwrellodoh', 'holdlerw ol',
//   'lrlewdhol o', 'lll wohdeor', 'hwrlledl oo', 'elrooh lwld', 'ewrlo lhdlo',
//   'hlloroelwd', 'h eodollwlr', 'wr ldleohlo', 'or ohldlwel', 'lohe lowlrd',
//   'rhdwoelllo ', 'owhorldell ', 'rlle ohdolw', 'rhlwolle od', 'woro helldl' ]

# ex-sync.R
needs(magrittr)
set.seed(512)
do.call(rep, input) %>% 
  strsplit(NULL) %>% 
  sapply(sample) %>% 
  apply(2, paste, collapse = "")

Asynchronous

// example.js

var attitude = JSON.parse(
  require("fs").readFileSync("example/attitude.json", "utf8"));

R("example/ex-async.R")
  .data({df: attitude, nGroups: 3, fxn: "mean" })
  .call(function(err, d) {
    if (err) throw err;
    console.log(d);
  });
  
// [ { group: '(40,55]', rating: 46.7143, advance: 41.1429 },
//   { group: '(55,70]', rating: 64.6154, advance: 41.9231 },
//   { group: '(70,85]', rating: 77.2, advance: 45.5 } ]

# ex-async.R
needs(dplyr)
attach(input[[1]])

return("early returns are ignored")
cat("so are undirected calls to cat")
print("or print")
cat("unless directed to a file", file = "out.Rout")

# output of final expression is returned to node
df %>% 
  mutate(group = cut(rating, nGroups, ordered = T)) %>% 
  group_by(group) %>% 
  summarize_each(funs_(fxn)) %>%
  select(group, rating, advance) %>%
  mutate(group = as.character(group))

Syntax

R(path)

Creates a new object that will source the R script specified by path.

R.data(...)

Adds data to the object and returns itself. You can give any number of arguments of different types.

R.call(options, callback)

Calls R. Any previously supplied data is stringified into JSON and passed to R, where it's converted into a list and loaded into the R environment as the variable input. On completion, the callback is invoked with two arguments: any error and the output from R, parsed back into a Javascript object.

Additional arguments for the conversion from R to JSON can be specified as options (see documentation for toJSON from the R package jsonlite for defaults).

R.callSync(options)

The same as above, but calls R synchronously.